I find it strange because neither Netflix nor YouTube depend on apps as you mentioned. They lose nothing by having their apps run on Rosetta 2. Apps merely make for an (arguably) smoother experience which is why I see no reason for them opting out. Their monetization strategies will work either way.
But if a videogame that costs money on a Windows PC is made free on M1-powered devices because of an iOS variant (cough, Among Us), I can see developers opting out.