I am a die hard prewasher. I am also cheap and a fabricaholic so I don't buy precuts and prefer yardage. Occasionally I will get a fat quarter or fat eighth and I don't hesitate to toss those in the washer.
If I ever got something like a jelly roll or other precut package as a gift or won in a raffle basket I probably wouldn't prewash it due to the raveling issues, not even by hand. Chances are I would regift it.