I asked if there is a new wave, since your post implied some matter of urgency because of a currently bad situation.
But the main waves are over, or at least the spam filters of Itch catch most of it. The filter is so aggressive that you now only see users complain that they triggered a false positive - and their accounts do not get nuked righ away, they can even still post in public community. At the height of the wave you saw developers complain about having to remove all the spam or how they would close comments because of that.
Now there is no wave and you urge developers to close comment section. That did not make sense. Your suggestion boils down to: have a (better) spam detector. And they already do have one (and do work on it).
Also, developers do not need to downvote comments. They can delete and remove any comment. And a report of a comment goes to the developer as well. This is currently hidden behind some clicks and not very visible. leafo mentioned that this is going to be improved, but not when.
Hiding comments is not something Itch would do. Especially not on something flimsy as downvotes. Plus, you would need those downvotes on spam comments to begin with. And only on spam comments. People downvote all sorts of comments for all sorts of reasons. Including comments from the developer.