I think the problem with Rainbow isn't the quantum generation, it's the card selection. Rainbow gets lots and lots of quanta at the end of the game, yes, but this is balanced by the fact that they can't really play most of their cards without a Supernova until the mid to late game, unless they get really lucky.
The main fact remains, though, that Rainbow is so much more powerful because it has over 100 cards to choose from, where mono has like 15 or so... Mono, however, has speed and reliability on its side, just like in any other game. For example, look at Dark Matter - 90% of Rainbow players insta-quit, because it's almost a given loss anyways. Devourer, as well, can kill Rainbow if you get just a little bit unlucky.
I've played these games for a long time, and people complain about anything that gets 'too powerful'...the fact is that Rainbow has been tweaked to the point of perfection by many people, due to the lack of card base...this means that to beat it, you have to have a specialized strategy that will lose to anything else.
At least until more cards are introduced to give mono and duo a fighting chance. However, nerfing Rainbow by changing pillars now will make Mono that much more powerful when new cards are introduced
