I give you a 100% upvote because this is probably one of the best posts created on Splintertalk so far. However, I fully disagree with you on pretty much all of your assumptions.

First of all, your level 5 summoners are simply not designed to play in Diamond League. Of course you will be matched against maxed cards there because that league has no limits. Instead, you should drop down to Gold League and compete for the league ladder to win some extra Booster Packs. It is actually more profitable to do so than just getting more chests on higher leagues. And it is way more motivating and challenging. This mind-set has not reached many players yet, who are still just trying to advance to higher leagues and ignore the leaderboards, probably thinking they could not get there or they are not worth it.

Further, the rewards will be adjusted in a month or so, when enough observation with the current system has been made.

And finally, the game is always trying to find a balance between rewarding investors and skilled players, while fighting the bot armies trying to leach out rewards, apparently unavoidable on a blockchain game without identification process.