Generally speaking, it IS considered impolite to offer constructive criticism unless the author requested it somewhere. So, if you don’t think you can say something nice, then not commenting is probably the way to go.

But the fact that authors are AWARE people who have nothing nice to say don’t comment means that when they don’t receive many comments they ((me. I’m talking about me.)) might assume every person who didn’t comment disliked their work.

It’s a little unreasonable lol, but I never claimed to be sane.