Seems you've had a bad experience with mentions. Maybe people have been using them in the wrong way, where you've seen them. At work, we were using Slack, and

Seems you've had a bad experience with mentions. Maybe people have been using them in the wrong way, where you've seen them. At work, we were using Slack, and @mentioned each other "all the time", and I'm fairly positive we would have abandoned Slack if people couldn't mention each other. Mentions are like going to the other person, and saying, "Hi, look there, you knowledeg & help is needed over here a short while". And then the other person takes a look, replies with help or status update for example. Our mentions were related to none of driving clicks or opens or engagemenet — instead, it was about getting work done, directly rather than ... some day later when the person happened to maybe see the relevant comments.