GOG is not slow with Linux support. It is non-existent.
Yeah, at this point, it's my main annoyance with them, especially for the games that are Linux compatible already.
I can understand them being reluctant to add Linux compatibility to a game that has none, but it doesn't take a lot of work to support what is already there.
I can't see developers not being on board with this, they usually want to sell their games.