Then they started restricting your team choices. You could no longer have two of the same hero.
You then had to be forced into meta-roles ONLY.
You then had to queue specific roles and were not allowed to pick anything else at all.
All lack of balance and content aside, what the hell?
The worst part is/was (unsure if this has changed) that you are hard locked into specific hero categories even if you are queued as a full premade. Even when you are with a full team that is OK with swapping, you can't swap roles as needed. Incidentally, I played dps junkrat back when it was categorised as a defence hero. And the categories were decided and changed by Blizzard - Junkrat might have been the only defense hero I'd be willing to play, and now the only offense hero since they recategorised him - I would rather heal than play mccree, but there you have it
This has been a criticism of Overwatch since day one. If the core problem was the actual core formula it wouldn't have grown so large to begin with. Millions of people wouldn't have billions of hours into the game in the first place if the core formula wasn't fun. I think you have a valid point, but I don't think it's why Overwatch hemorrhages players. None of the issues your brought up are any different than they were for the past 5 years (except role queue).
Also, you can't point to queue times, then mention League has a better system. It wasn't rare at one point (I don't play League anymore) to have 30 minute queues even in diamond. DPS queues in OW currently are 10 minutes max even in GrandMaster.