My very impressionistic (made up) view is that passage of ACA made some things definitely better but also put in a place a new era in which insurance companies and the medical providers (hospitals, doctors) generally behaved a bit better, not precisely because they were forced to but because everyone was still sorting out the new system and figuring out where the opportunities for abuse were.
Poke at the defenses and if nothing hits back, go grab the cash (send people 5 figure+ bills and ruin their lives).
And a dozen years later, things are as bad or worse than they were before ACA, generally, though there are some nontrivial specific improvements. And it'll take another 10 years (if we're still here) to do anything about it.
