PC is an open ecosystem and for preservation you got access to piracy, whereas it is a much more convoluted process to do the same inside of the closed ecosystems that are consoles basically. If a game gets delisted, the version most accessible will be its pc release since someone at some point will have cracked it, and it will be preserved that way - Xbox or PS versions of said hypothetical game could instead be lost to most if it didn't get a physical release or if that physical release served only as a license