I guess it might be because those of us who actually do support the blackout tries to keep staying away until things changes, while a lot of the people on Reddit right now have been content starved for a few days and just waited for the subs to open again (and thus does not want to see them shut down again).

Personally I quite like it here on the fediverse and am not in any way in a hurry to go back to Reddit any time soon.