I think the main idea here, which is also Mendelson's complaint in her Home Comforts book, is that labels *used* to be the harshest safe cleaning process for the garment, thus t-shirts, towels, jeans etc used to just say "machine wash and dry" or even "machine wash hot, tumble dry hot" and that was it, to now they are covering their asses and saying "machine wash gentle cycle cold, dry flat", which is basically not only wrong, it's just slightly less wrong than the other folks that print "dry clean only" for the same garments.
And I understand me, as a man, belong to a privileged slice of the population: I *know* my measurements, *all* I have to do is buy t-shirts, pants, shirts etc to my measurements, I don't even have to try them on. And there are places that do *not* make clothes properly, they *should* be preshrinking the fabric, then making the garment, they instead buy fabric and make the garment that will then during the first 2-3 washes shrink to fit the measurements.
People who buy garments like dresses, which say "size 6" are out of luck -- to begin with, they may be size 6 on that label, size 4 on the next, size 8 for a third brand, and when they try the garment it fits in the store, if they shrink after washing it will be more than just annoying.
The problem really is, that if the fabric has not been pre-shrunk, you can kiss garment stability goodbye, because it *will* shrink, it may take 6 washings, but no matter what you do, cold wash, dry flat under away from sun etc, it does not matter, natural fabrics shrink it's what they do. The only good way to deal with it properly is to at some point wash it in very hot water and dry on hot too, then it's usually stable.