BH isn't getting any special treatment. Its concept is hacked Pokémon. You can hack unreleased data. Mix and Mega's concept is Mega Stones working on all Pokémon; everything else remains unchanged.After looking at this more carefully, there's some really big flaws with this reasoning.
For one, the door is already open. Balanced Hackmons, as you admit, is already getting this special treatment, so why should Mix and Mega not? They're admittedly two very similar metagames that consist of mechancs that are not achievable in the real games. As the post above me put in very good words: the ultimate similarity between Balanced Hackmons and Mix and Mega is that they're simply designed for fun and, again, do not follow the mechanics of the real games. It should not have the limitations from the real games as it's not based on the real game itself. This was the reasoning behind BH, so again, what makes Mix and Mega different? You're already giving special treatment to one OM as you said, so that part of the reasoning becomes completely unnecessary and untrue. As for "opening the door to other metagames," I believe that Mix and Mega is already one of the most unique, and unachievable-in-reality metagames that we have (EVEN MORESO than BH) so this would be a fair exception. My firm belief is that OMs should focus on fun rather than having resemblance to any tier (come on now, the point of OMs is to literally be distinguishable from standard tiers already).
I think Mix and Mega will not have any resemblance to any standard tier as long as we allow six mega evolutions per game and allow any stone to be used on any Pokemon, so I do not get this point. It lacks any real resemblance to the real games already, so why should this be a problem? If you really wanted to resemble actual tiers, wouldn't you focus more on limiting the amount of Megas per team?
I'm tagging The Immortal and scpinion to strongly urge them to reconsider this decision. There's no valid reason to limit the enjoyment of a metagame that already is only playable on an online Pokemon simulator and which the whole basis of is unachievable mechanics that do not have any resemblance to standard tiers.
I've already said this before but don't use this thread to argue the matter. Feel free to urge us outside of this thread.