It is one of those semi grey areas in the written rules that Blizz has clarified via blue posts. Making a thread to call out another player by name, for any reason, can get it removed. Most of the time call out threads are negative to accuse someone of something like botting, or to instigate fights. Rarely are they constructive and positive. Blizzard considers call out threads Harassment or Trolling, depending on what is going on.
Rarely, the thread using someone’s name is neutral or positive. Even those are technically not allowed.
So, you were not wrong about the rules and it still comes up from time to time. Question for Miss Cheetah - #21 by Nevalistis
We don’t permit the calling out of others on these forums, for any reason, and the fact corrections that need to have been stated have already taken place, so I’m locking this down.