I don't know but similar can be found on https://wiki.winehq.org/Clean_Room_Guidelines

"Don't look at ReactOS code either (not even header files). A lot of it was reverse-engineered using methods that are not appropriate for Wine, and it's therefore not a usable source of information for us. [1]"

That looks strange and requires more information. ReactOS devs in past have submitted patches in Wine, since ReactOS itself uses some parts from Wine.

ReactOS takes from Wine, but Wine does not want to take from ReactOS any longer.

Not surprising when you compare some leaked NT code and some ReactOS code. I'm not even saying they straight copied the source btw, but some consider that disassembling as a reference is fine (and using MS symbols...). Well it might even be legal in some cases (more cases that some licence-aware people commonly imagine), but this is a really risky stance to take. For sure ReactOS is very far from clean-room.

I think there are more reasons. Maybe let's move this discussion here https://news.ycombinator.com/item?id=40730327 I don't want to make this thread shit-post.