Separate the original and competitive ranked modes
I can't see any possible ways to satisfy both kinds of players in one ranked mode.
Then why not make a new mode? Name it competitive or championship mode.
The most obvious problem is dividing the queue of ranked.
How about making the new mode limited-time? Like the rank ladder, 3 days on, 3 days off.
The original ranked mode is still 24/7, the main game mode to grind.
The new mode can be or should be insanely competitive. Drop zone, solo queue. They can try only the winning team gains points. It is more acceptable to reduce the difficulty than increase it later.
When the competitive mode isn't live, or you don't enjoy it, or let's say it requires solo queue but you're 3-stacking, you can still play the original ranked mode.
I prefer that the two modes be completely separate. Pred can still get to pred without playing the new mode. You don't have to grind both sides unless you want.
If no one queues the new mode, that means no one wants to be that serious in a video game, but I think there should be at least 1 mode for people who enjoy playing seriously.