One of the things I found annoying on reddit was when people would cry about getting downvote instead of making a comment without worrying about whether they got downvoted or not.
Making edits crying about getting downvoted or first saying I’ll probably be downvoted for this but… I really disliked those.
But, I will agree that it is preferable to leave a message explaining why someone disagrees rather than just downvoting. Whining about it is just as annoying though. If my instance let me downvote I’d downvote those comments even if I agreed.
If there’s a more active community it could be a good idea to have the community locked but have a thread redirecting visitors to the other community to help the one that’s still alive grow.