Yeah, I wish posts would straight up not mention the total number of accounts. It's not something to brag about. A significant number of the difference between active vs total is gonna be bots. Especially since we're so new. If active is monthly, then active would include almost anyone who has actually used their account.

The active users count is probably inflated for a bit, too, due to people making multiple accounts as they switch instances or try new ones out. e.g., I used a kbin account early on before switching to try Lemmy. I also have a Beehaw account that was actually the very first one I signed up for and gave up on because of the manual approval taking too long, yet I think I may have posted at least one comment cause I used it to try Lemmy first, then switched to an instance that had downvotes and didn't defederate as many instances. So I'm counted for probably triple. On the long run, I'll probably end up using just one of these accounts, but that would depend on features. I switched to Lemmy because of the features it had and if kbin gets better, I might switch back.

EDIT: oh, right, and then there's also porn accounts. The way Lemmy works makes you almost surely want a separate account for the porn instances. It's easiest to browse those instances by local posts, but that requires you make an account there (it also won't show NSFW without an account, which is a silly barrier that is just going to hurt adoption). As well, voting is public, so if you want to privately vote on NSFW stuff, you should use a separate account. By comparison, on reddit, as long as you didn't intend to post or comment, there was no reason to use a separate account for Porn.

There have already been instances found that had thousands of bot accounts, they've been defederated but clearly people are gearing up

huh? What's tumblr got to do with this? Is this about Automattic adding the ability to connect up Tumblr accounts to the fediverse? Because you do know that isn't the same as the Threads situation right?

It's very probably going to function like how Wordpress and ActivityPub already functions - as a way to let people look at and interact with your blog from a Mastodon or other instance. And if Wordpress is anything to go by it'll also probably be limited to self hosted/paid accounts rather than something that everyone can have so the bot/spam/ghost account worry is kinda moot