Plus, if there happens to be a flaw, one can spot it while ironing/pressing it.
I "tag" fabrics that have a flaw with a small safety pin on the selvage near where the problem is.
I feel that not washing quilt fabrics before cutting them is like having unprotected (consensual) sex - most of the time there will be no physical problems/issues - sometimes there are - and it is a lot easier to prevent/avoid them than to try to fix/repair/cure/undo them.
(Let's see how long this comment stays on here!)