The GP comment is just another example of how there's a ton of uninformed anger on this issue. People are spitting mad because they're realizing that health care is becoming really expensive, and they think the ACA is to blame because they heard about the ACA last. The amount of actual understanding approaches zero, because few people pay for their own healthcare in the USA.
I kind of want the GOP to just burn everything down and expose everyone to the full pain of this absurd system (in true, "free market" fashion). We'll have a political revolution overnight.
You can argue that cost increases are due to all of those previously uninsured sick people who are now insured and costing the rest of us money, but that's both wrong (costs have been going up faster than inflation for decades), and a pretty awful worldview.
And despite all of that, health care cost growth still dropped
What I read, and I did read this online and haven't had the time to look for primary sources so please take with a grain of salt, but worth looking into is this:
pre-existing condition check was a major risk to the insurance industry since nobody knew how much it was going to cost them. So the ACA told insurance companies we'll subsidize some of your costs until things settle down (this is different than subsidizing people's payments). However when it came time for the gov to pay, Republicans blocked most of the subsidy payments to health insurance companies (I think they only received 12% of the expected amount).
And then because insurance companies didn't get that subsidy they obviously passed the cost onto consumers. And I'm sure whatever subsidy was further promised by the Gov they could no longer rely on so they priced that risk in as well.