I gave some pretty high-profile examples (RTS being at least somewhat comparable in terms of genre, with Unreal Tournament being a dissimilar but massively-successful FPS franchise). I don't have the time to sit here listing negative community reactions to game sequels. They're everywhere. People will often stick with what's familiar to them, it's Psychology 101.
Nevermind the fact that people having played Civilisation 6 before going back to Civilisation 5 has very little to do with Civilisation 6 being a bad game. It just means they prefer a game with six years of support and modding projects behind it (or consider Civilisation 6 a bad game; it's not all of one or the other).
Simply put, you're wrong. You're making an assumptive leap where you shouldn't be.
Nevermind the fact that people having played Civilisation 6 before going back to Civilisation 5 has very little to do with Civilisation 6 being a bad game. It just means they prefer a game with six years of support and modding projects behind it (or consider Civilisation 6 a bad game; it's not all of one or the other).
Simply put, you're wrong. You're making an assumptive leap where you shouldn't be.