Maighstir: 1: sometimes they can't.
2: yes.
xa0c: Thanks for quick reply. Actually if the 2nd answer is yes, then 1st one doesn't really matter :)
To expand a bit:
Sometimes there's no time to inform about a future scheduled removal as the game needs to be gone from the store yesterday. And it does matter, primarily to people who are on the fence of getting the game. If they know it'll be gone soon, they may very well get it while it's still there.
Removal from the store and removal customers' libraries are different things. Games may
change in libraries, however, like an extra or a non-Windows release may get removed* - but that's similar to a game being updated, the game package is
modified both for what's being sold and those who already bought it. But changes in the library mostly happens when the game is still being sold (if it's not being sold, the developers rarely bother sending updates to GOG for packaging).
* I can't remember the game, but there was one where a third-party studio had ported the game to MacOS and/or Linux, and held some rights to those. GOG had initially released the game for both Windows and whichever the other platform was, but the other had to be removed since the porting studio hadn't agreed.
* Another one was when the MacOS release of Fallout was changed from being the DOS version run through DOSBox to the Windows version run through Wine. Of course, after Bethesda took over completely, they didn't agree to sell the game for MacOS at all, so GOG made a new package for Bethesda so that older customers could keep theirs.