I think your idea has some merit.

It would minimize the situation that I face all the time in 5v5s - we meet teams in the 1400s that have 2 unskilled, badly geared people and 3 challengers/duelists/gladiators. After getting stomped by them numerous times I've looked a few of them up and they are on the 8th or 13th highest ranked 2v2s and 3v3s in our battlegroup. What, exactly, are they doing playing teams ranked 1420 and winning for 15 points?

About half the teams I have faced are of this makeup. I guess selling teams wasn't OK, but selling skill on a crappy team is OK. I'm not mad at them, they are just exploiting what Blizzard allows them to exploit. But it makes entering arena at 1500 a bit choppy.

People could still get around this in your system (gladiator eventually gets up to a 5v5 PR of 2100 by PowerLeveling teams up from 1400 to 1700 several times, then spends some of his proceeds on a new team and AFKs 38 matches till his 5v5 PR gets down to 1300, then starts again), but at least they'd have to work for it a little bit.