I log in, mostly so my IP doesn't get put on blast in the log.

I log in. Mostly for nostalgia, (I started the resilience wikipedia page and still regret doing it without an account!) but also for skipping the annoying pledge banners.

I'm not sure thats true since it's a policy violation (without proper disclosure) that is fairly regularly enforced when found

I wouldn't say that's a common practice.

I always log in to edit, then log out.

I log in mostly for the custom CSS.