Are seedlings as delicate as we are told?

I have been starting seeds for 4 or 5 years now. I thought I had it down, but this year squashed my ego for sure. I know the mistakes I made, and at least I hope I learned from my mistakes.
The few seedlings I didn't manage to kill were some tomatoes. They were started in 3/4" soil blocks. Potted up into a 2" soil block. I moved them into the greenhouse where they survived for a couple of months. I didn't pot them up. They endured day time temps up to 111, and night temps of low 40s. How they survived I really don't know. Not surprising they look terrible! My first thought is I should just buy a few plants, and toss my seedlings in the compost.  I just couldn't do it. Everything I watch and read says they will not come back from this, won't grow well or be productive. And yet, I know this is silly, but I feel like they deserve a chance, they have endured and deserve better. I have a few tomatoes I started later so if what , "they" say is true I should still get some tomatoes.
The thing is the few I planted 10 days to 2 weeks ago are looking great. I would say they have doubled in size, and greening up. If I didn't know better I would think they were different plants. The jury is still out of course, they may not produce, but they are sure seem to be growing well. The small one is about 8 to 10 inches tall because I planted it quite deep. The larger one was planted deep also, maybe not as deep, but I would also say it seems to like where it's been planted, or it's just a fast grower. time will tell.
Now I'm wondering if I have waisted sad seedlings thinking they were a waist of time and space.
What do you think? Are veggie seedlings delicate or tough?  What is your experience with sad seedlings?

Tomatoes are tougher than they look honestly. I've had them survive conditions I was sure would finish them off and then keel over from something completely mundane. The soil block method probably helped a lot, roots stay intact and don't get the transplant shock that kills most seedlings. The extreme temp swings are rough but tomatoes seem to handle stress better once they've got a decent root system going.

Tomatoes are tough. One year, I bought a 6 pack of plants. I put them in a safe with sunlight spot. Far from my daily path. Several times, I found them limp and prostrate on the surface for lack of water. Ahem.

They recovered and produced well.

Those seedlings look too big for the pot they are in to me. They've run out of root-space. No wonder the ones you planted out grew like crazy - you gave them the one thing they were lacking!

Go, little tomatoes, go!

I replanted aubergines and cucumbers and sweet peppers and tomatos. Some cucumbers died, the rest looks like standstill, but the tomatos looked just like nothing had happened, i didn't even feel like watering them and wondered if tomato plants are tough cookies? So there is my awnser. Thanks. Your poor tomato plants! Hope they recover completely and will do great.
On the internet they always play safe and like to say things like throw it away, buy new, but they do everything standard chemical farming so their soil is dead. mine was filled with mycelium threads throughout. I don't know if that is so great, but at least it isn't dead.

I was given a tomato seedling at an event I attended. It was in a small coir pot which wasn't even filled to the top with whatever the donor had used as "soil". At the time, my window ledge was overflowing and I wasn't coping, so the little seedling was lucky to get water, and it responded with stunted growth and poor colour compared to the seedlings I'd started myself. Two of my seedlings got so tall that I had to chop the tops off. I stuck the tops in a jar of water for a day while I sorted out a couple of pots with some good compost soil mix which I lightened with coir/perlite to see if they'd grow roots. Those tops thrived also.

So I got the big plants in the soil about a week ago, giving me room/time to transplant the donor tomato. It got a larger, but not huge pot with my good home mixed seed starting soil which is heavy on compost as I think seeds need the microorganisms that represents. It still didn't seem happy after a couple more days, so I decided to try something a little extra. I had dried some Stinging Nettle for whatever I might need it for (add to tea or soup maybe?) I crushed a bit in a small jar, added water, and set it on the window ledge. The next morning the water had turned a lovely green colour. I watered the donor plant and the two tomato tops with some of the water, and later gave donor seedling a second dose. The combination of more/better dirt and a little liquid "fertilizer" seems to have done the job. In 3 days it grew at least 2 inches and the new leaves all looked a healthy green colour.

The weather's turned chilly again, so I'm not sure I want to put it out yet. I ought to make the time to put it out for a few hours to give it some "hardening off" - another thing my set-up is not conducive to - half flight of stairs and a door that sticks!

But I too have found that plants can be tougher than we think.

Another hint for indoor seed starting mentioned elsewhere on permies - yes, a fan blowing on them at least every couple days for at least an hour, really decreases their tendency to get leggy. That's assuming you can't start them where Mother Nature will provide that wind!

Ideally we could all direct seed. There are ecosystems where I know it's successful. There are ecosystems where I know that it should be experimented with. Alas, I have had *no* luck with direct seeding. I probably shouldn't grow tomatoes - we just don't get the summer heat that they like, and our nights cool off due to on-shore breezes. But tomatoes warm from the garden are awesome, and tomato sauce in the winter is awesome, so I compromise.

I did manage to start tomatoes directly in the garden one year, and they did produce, but I lost half my production time.  I direct sow almost everything except tomatoes, peppers, and I like to play around with other stuff like herbs and flowers.
From what everyone is saying I guess I better plant those tomatoes and give them a chance.  It also sounds like maybe most seedlings are not as tough as tomatoes.
Thanks everyone it's been interesting.

How do I deal with sick seedlings...

I grow extra with multiple plantings...       planting at different times, so I have backup plants for when the plants I made don't make it for whatever reason.

I also have improved the soil the seeds go into by making my own compost mix.

One of the reasons I stack food on the shelf is that there are gonna be years the food just does not work out for you, and being ready for that I find a wise move.