Dandelions, purslane, lambs quarter, sorrel, thistle, mullein, and other useful "weeds"; they're certainly welcome in MY garden! Thing is, if one leaves a garden untended, the grass usually takes over.
I have heard many times some variation of "the only thing i don't allow in my garden is grass" or "i absolutely don't tolerate grasses!" thing is, if i go through and cultivate my garden with a hoe, i'm going to get everything if not everything EXCEPT grasses because grass recovers faster from hoeing than anything else i'm aware of. So what are these fellow gardeners doing that allows these beneficial "weeds" to grow but not the grasses? Surely they aren't on their hands and knees, hand weeding 1,000 sq ft gardens, are they?