You will still have to end up deciding for yourself whether or not to prewash your fabrics before cutting.
You won't even get a "majority vote" on this one.
I think everything that is prewashable that goes into an item should be washed before it is cut. (I've measured "before and after" - and I think it's worth the effort.)
There are others that say they see absolutely no reason to bother.
(Of course, there are also people that saw no reason to use a seat belt or use birth control -MOST of the time they were fine - -- )