It is not uncommon for words in English to have variants which are slightly longer than they need to be, and our collective response to these words is somewhat capricious; some of them make people Very Angry (irregardless, conversate, preventative), while others (commentator) seem to elicit little more than a shrug.
Yeah, I take issue with all of these, including commentator, despite it being commonly used. Just say commenter. They’re commenting. I don’t care for all these extra taters.