Probably because it's kind of useless. No offense, but it's so easy to make a trigger like this, it's not going to hold up on it's own.
If you develop it more, like adding AI for summoned units or something, then it could be useful. But as is, it's not worth keeping up - there's just not enough there
I do know this - xenforo dropped the ball by not keeping the vbulletin reputation comments as a feature. The loss of the Reputation comments data when we switched to Xenforo really was the death knell for the site when it came to all the users that left. I know I missed it so much and I got way less interested in the site when that feature was gone and I run the site.
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory