I don't understand your problem, with the new focus system you earn rshares with every win even if you don't use a card from the focus, you get now "only" a bonus for focus-cards, so you can really play everytime the best team and earn focus points for focus chests and season chests.
So it is in my opinion better than before where you should decide if you want have a higher winrate or success in your focus. It is clear that some rulesets are better for one splinter and other rulesets are better for another splinter. Even with a lot of summoner of every element in the game it stays in that way, f.e. live is probably not the best choice in "unprotected".