The % of people who care might be small, but it is that same tiny percentage who have the largest impact, and who are crucial to the smooth functioning of reddit.

If they all leave or get booted, reddit will noticeably change for the worse and a larger % of users will leave with them. I can only hope that the number of users fleeing to new platforms like Lemmy is sufficient to make them viable and strong alternatives.

If all the cool kids leave and set up shop elsewhere, reddit will be seen as outdated and people will start to leave it behind. Especially if Lemmy goes enough to gain unique new features/communities/traditions/memes/etc. Digg was abandoned so quickly in part because reddit was already there, complete with its own community, in-jokes, and sense of community for people to join in with and feel part of. Lemmy isn't there yet, but fingers crossed there are enough people involved now to have reached a critical mass that drives increased adoption.