Why do people/accounts join and make 0 posts, never logging in again?

[Warmmedown]

Won't name names in case they come back, but in the current "newest members" 4 of the 12 are like this. Join date same as last login date, and 0 posts. Even if they're bots, what's the purpose of not making posts to advertise anything and then never logging in again? They can't even monitor the forum.
If they are real people, I've signed up to sites and then never posted because I wanted to look at something that required login, but there's little reason for anyone to feel that about Zeta, since the anime sections are public (the only tell is any mentions of the other sections in public posts, like right now). Other sites have annoying validation measures, like needing to sign in to my email to verify the account.

 

[SSJ2]

They are bots and get stuck at the email confirmation stage. They can't verify their account and can't post. The same goes for anyone who signs up with a fake email.

That page is also not accurate. There are a good 30-50 accounts signing up every day that aren't shown there. Some real people as well that never posted.

 

[Warmmedown]

That raises another question of how some bots are able to get verified and then make a spam post. Unless they're not bots and are people paid to post adverts.