I don't like this, because it legitimizes not correctly marking platforms on the part of the developer. If you see an incorrectly marked game, report it!
Itch could also do a better job of catching incorrectly marked games. If it contains a .exe file, it's probably a Windows download even if the developer didn't mark it as such (although it could also be a DOS download).
There's a big share of things (game or not) that aren't executables (e.g. PDFs) which don't fall under the current win/mac/linux/android classification
I'd argue that allowing downloads of unmarked platforms in browser already counts as legitimizing incorrect platform marking (and if that is an issue itch should have forced platform marking w/ an "others" option included too)
