I watch for this issue too since it's something that I don't really like in this game and honestly those you mentioned are the least offenders. It's still good to get the crit out, but if you're only hitting the really visible people you're missing the players who do this all the time and get away with it and it makes you look kinda grudging. Not saying they don't have this problem but your pattern here is missing the bigger picture which is kinda weird. Just looking at their most recent posts, some threads are longer than others because the people they're tagging with reply faster than others. This is a strong consistency.

Again, talk with them if you feel this is a problem, but from where I'm standing they're not the problem. There are much bigger offenders and it's surprising you didn't mention them especially in your latter comments.