What is the fundamental difference in this situation for mirror matches and other map types? Everyone has always played this way, and no questions have ever arisen.
And if I intentionally sacrifice a hero on a dividing line, can't I resurrect him either?
Or if I have 100,000 gold and deliberately dismiss a hero with no movement points, so I can resurrect him and attack my opponent? Can't I buy him back either?
In the future, I hope this loophole will be closed (at least in mirror matches), and for now, we'll close it with a verbal rule.
The fact that the "dismiss and buy back for 100,000" tactic is no longer possible is not a big loss; it's used in maybe 1 out of 500 games anyway. Final battles with a pawn exchange happen much more often, so they are a higher priority.