I believe your tomatoes succumbed to blight because the tomato plants themselves weren't completely healthy and couldn't fight off the disease. The tomato plants aren't healthy because there are mineral deficiencies and imbalances in the soil. Plant diseases are everywhere, and in everyones soil, and only manifest themselves in plants that can't defend themselves. Granted, yes some diseases pressures can get really bad by planting the same thing over and over in the same area without crop rotation. Conventional gardeners and often (but not always) those who work at garden centers will say you need chemical sprays to control the disease, which is entirely untrue. Don't believe it.
Remineralizing your soil will bring things into balance, allowing the good bacteria and fungi to thrive in the soil, which will in turn cause teeming populations of the good guys in the soil which will subdue a lot of the bad guys in the soil, and the plants you grow in this soil will thrive, having all the necessary mineral nutrients they need to have a healthy immune response and will not be adversely affected by diseases. This starts with getting a soil test from a lab (I myself use Logan Labs, the test costs $25) and with this information, and some calculations, which I am happy to help you with, you will know how much of what minerals you need to add to the soil to build your own
super soil.
It also goes to mention adding organic matter like quality finished
compost to this soil is a good idea and will certainly help.
It may sounds too good to be true, but it isn't. I've been working on remineralizing my garden soil, and this year is the best so far, with little disease manifestation, far less than any year prior. I used to use OMRI listed organic disease controls, this year I didn't spray anything in my garden. Not only will the plants thrive and not succumb to diseases, the fruit they bear will be super nutrient dense and delicious!