It's usually not done for benefit of anyone but themselves, parting with an interest and/or community that may have been a central part of their everyday life for years.
By the same token, people rationalising their personal feelings can draw flak on their intent and legitimacy of emotion (lol) regarding Current Thing because other people have comparable stakes in Current Thing insofar as it is the cornerstone of their own interest and identity in the community. Then the nostalgia of the former - who perceive a radical transformation of their experience of The Thing - chafes against the latter - who came because of the change and only now experience The Thing - precipitating conflict, erecting ideologies, radicalising, polarising, all-around making things miserable. Being able to say goodbye to something you once liked and then walk away is laudable, all things considered. FGO ain't even the first time it's happened on BL.