So what are the checkmarks about? Seems to be only in the Community Center topic.
checkMarks

I think I found the answer...

It's a hint to how much kudos the thread starter has (an algorithm based on their reputation, solved threads, and endorsements), to help you judge the quality of the question being asked.

Useful??

Do the check marks still exist? I don't see them anymore?

No, they don't. They were replaced with the lil "OP Kudos" prefix next to threads that would have gotten checkmarks.

Oh, that makes sense