Hi, I'm surprised that this post has no comment yet, I was thinking the same thing. Sellers are always complaining about bad experiences with buyers but you seldom see these buyers with bad reviews. In my opinion, even if you don't want to outrightly give a 2 star, you could hint other sellers with your comments cause bad buyers could also have behaviours you like about them. Like "Buyer communicates his expectations excellently, this helped the project. He doesn't accept delivered orders, he lets them auto complete or He takes his time to respond to messages after initial conversation to kickstart order".
I think this will make buyers adjust without causing much damage. Lol.