I am also against a "max cards only in Champ" requirement. Despite maintaining a max level modern core deck, some promo cards I didn't level up intentionally because cost/benefit didn't justify it, and some I still can't justify (or there aren't enough on market to buy at a reasonable price or at all if I wanted to). Strategically not leveling up a few cards is also a thing, but that is rare I think. Reward cards are obviously another fault with this requirement since it takes time to level them.

Applying the level requirements to archons/summoners only is a great compromise. That keeps Champion as an "elite" division - most players there will have mostly max cards, so putting the limit on the archon/summoner only would keep most unleveled decks out of the division, but still allow for not having everything at max level. I think few people would level up the archons/summoners just to play in Champ, without also leveling up most of their cards (because they'd get wrecked otherwise!). There'd be little point in having a sub-league of schemers trying to cheat the system because the earnings would be tiny compared to the cost of maxed archons/summoners. The R share formula could also be modified to take card level into account to drastically further reduce any SPS/Glint rewards a player could earning doing that.

Diamond would be your division if you're working on leveling up your archons/summoners (and other cards) to reach Champ, and it justifies having both divisions.