What's this bullsh!t warning?

I don't want to try later. If I'm doing something right now, there's a good reason for it.
I've got a full schedule to fill in the rest of my day. Do you think I'll sit around and keep trying every once in a while to mark replies as Best Answers?
If you want engagement on this site, you don't put limits on trivial things like awarding Best Answers.
When you start actively hindering people from using features, they're going to stop using these features. They'll end up being redundant features because they absolutely suck.