Personally, I have no problem with the idea of Mythic raids scaling to 10 players. But I also haven’t stepped one foot into a non-LFR raid since Wrath of the Lich King, so my opinion doesn’t really matter on this subject.
Most players don’t even clear Heroic raids. Find a guild to run Normal and Heroic, and then when you’ve mastered all of that you can see if you still dislike the entire idea of a Mythic raid with more than 10 players. Right now, it sounds like you aren’t raiding at all. It’s very awesome that you are confident in your ability and really want to clear the hardest content, but you should clear the other modes first. You may find that the Heroic challenge is greater than your current ability (no offense intended).