Ultimately, the matchmaking system was working well for you, until you shot yourselves in the foot.
No, I'd blame that on the untimely death of TSFH
Anyway, you're deliberately ignoring the bigger issue which I highlighted in my first post in this thread:
If a bunch of new players came to the game and started a clan, they would have this problem. If a bunch of old players decided to break away from their previous clans and start an offshoot, this would happen.
Tacky is correct in his assessment that the current system privileges established clans and slows the growth of new ones.
Maybe that's the price to pay for accommodating other concerns, but it is at the very least a legitimate grievance and a trade-off.