The thing is that there are reply guys who are in it just to be a nuisance. My criticism is that they aren't trying to establish boundaries with innocent people, and that they resort to basically bullying people for trying to be nice, and have a conversation.
I don't fully agree with the notion that a microblog is a third place like, say, Lemmy or Reddit is. A profile can be incredibly personal, and there can be tools used to limit who sees it for that reason. A profile can either be a massive one with a massive audience, or one with a few of your friends following. Those both are very different. The third place would arguably the instance the user is posting on, and those have rules and expectations. Federated conversations are very different. It's more akin to a town full of third places. In the streets, you need to establish boundaries with people you're having a conversation with if you don't know them.
A reply guy is a /kind/ of troll, and identifying certain tactics is important.