I'm afraid I agree with this. Also, with my most recent concern, I found that I was posting an issue to the tracker, then responding by email to individuals from the mailing list who offered possible solutions. Some of the potentially useful information ended up in the tracker, but much of it got lost in emails that were more or less private. The record of what did and did not finally solve the problem is scattered about, not in a single place.
Moving to Github issues won't solve that - it would just move one of the places to a privately owned third party site over which we have no control.
We certainly would never want to try to move our primary communications to a tracker either - that would be horrific.