I think you hit the mail on the head. All social media succeeds based on their power users and community. If just a small amount of people switch, the platform sto of s exponentially growing which looks bad for advertising. Especially if all these people are the small percentage that helped moderate the entire platform.

Fully agree.

Also, I saw several subs who asked their members if they should join the blackout, so it's not really fair to say mod decided top down.

I don't disagree, they definitely have the right to do the blackout, it's within the power that Reddit gave them, but Reddit also has the right to kick them out and reopen those communities, which I think is effectively going to be the same as leaving subs unmoderated. Reddit is kicking out active mods in favour of inactive ones just to open subreddits, which could turn the site into an unmoderated mess for a while... at least until more suckers sign up to do free labour for a corporation that's shown they don't give two shits about them.