Lying by Omission is still lying. 343 was asked about how they intended to handle console vs PC. And I seem to recall they said, they would do it based on the inputs used, and how you could choose to only play with a specific input.
But they intentionally left out that if your party was a certain size or larger you would be forced into mixed input based match making. I think this was left out because they knew the amount of backlash they would receive about it. And it is tremendously frustrating.