GP isn’t entirely accurate. As we all know you can inflate your GP by polishing up crap toons.
This has been talked about ad naseum for TB.
I imagine guilds, close to moving up a threshold in GP tiers, will begin to require members to deflate their GP by removing mods from junk toons.
The match making may need to be refined at lower and mid tiers. However in the upper tiers, given full participation and no timeout/draw glitches (on individual battles), there is almost no way to avoid a tie.