Commenters...

...and commentators are not the same thing.

The first is a direct nominalization of "to comment". Ergo it refers to someone who comments. Like on this blog. As a form of another word, it does not get a separate dictionary definition.

A commentator is slightly different, he or she is someone who "discusses news, sports, weather or the like, as on TV or the radio" or "someone who makes commentaries".

The latter implies some analysis, the former is more reactive.

Clear?

Oh, and while we're talking word choice, I'm still waiting for someone to give me one scenario where "utilize" is a more appropriate choice than "use". Just one. It has yet to happen.