Readers can delete reviews/comments too! Might not be as often, but it happens.
I had this...somewhat obsessive reader posting condescending comments on almost every chapter in my story (and many paragraphs), calling my protagonist gay and using homophobic slurs. Apparently there was one time he posted the same comment twice (or double posted), and I think he deleted one of them. Since I usually respond through Inkstone, I didn't know he deleted one of them, so I replied to the first one. He received the notification in his inbox (or so I guess) and saw that I was replying to a deleted comment.
Guess what happened? He copied and pasted one of his comments, ranting about how my protagonist is a beta cuck white knight, etc. and then claimed that I deleted his comment. I was like, I've never deleted any of your comments, what the f are you talking about? He then proceeded to point me toward the WRONG comment...only to embarrass himself by admitting that he thought I deleted his insulting comment about beta cucks and whatever (way to jump into conclusions) and thus he decided to "out" me by copying and pasting the deleted comment (which I didn't delete because I had never deleted any of his comments at all, and he found out too late). And then he proceeded to declare that he will continue trolling me after an insincere apology.
So I pointed out that maybe, just maybe he deleted a double-copied comment of his own, and then he fell silent after that. And not before he deleted his inflammatory review.
Yeah, Readers Can and Will Delete Reviews/Comments too.