That’s a zero sum game. Why? Come back in 15 minutes and if somebody else has started typing in the meantime what do you do?
Don’t get me wrong, I am pro this feature. But it needs to be elegant, simple and most off all conducive to generating traffic, not preventing it.
Perhaps the solution is very simple. Allow the feature to be turned on or off dependent on the type of communication being discussed. For example, if anybody here would like to discuss the relationship between Paine and Jefferson with me, I’d expect each of our replies to be considered, widely spaced and probably quite lengthy. Presence feedback needed here? No. I’d post because I want my point to be recorded there and then, immaterial of what anybody else is doing.
On the other hand, in fast moving forums, especially where there is ordinal significance, presence would be welcome - even if we only show which logged in members are currently viewing the thread.
As @purldator put it:
To that I’d add, not just NodeBB, which incidentally I feel has much more going for it than presence, but even many of the most skeuomorphic of old school forums have this feature available in one form or another. And I worry that when I read discussion about potential new features on Meta, that they often become dead dogmas, simply because folks frequently focus on the negatives, rather than the positives.