The cost curve for individually-purchased health insurance has been bending. One Obamacare provision that contributes to that bending has received no public credit that I have seen:
The herding of policies into four levels of policies: Platinum, gold, silver, and copper.
If you took freshman economics, you learned the simplified pricing scheme: auction markets between identical products that results in identical prices at the lowest level at which they can be manufactured. If you examine the logic, auction markets between (objectively and subjectively) identical products would result in those lowest-possible prices.
For that reason, every new company starts with a business plan that emphasizes avoiding that situation. Manufacturers use advertising to gain subjective distinction from the products of their competitors. That doesn't work well in the insurance sector. "We pay our claims in shiny, fresh bills delivered by singing claims adjustors," wouldn't impress.
Insurers, particularly health insurers, competed by all writing slightly different policies -- actual, objective differences. (The Bush Medicare D program took this further with a system of having different companies covering different drugs. If you need drug X now, you choose a company which provides drug X; you take a risk on whether you'll need another drug later which the company might not cover. That is to say, you don't have insurance.)
Economists call this "asymmetry of information." The buyer has less information on what they're buying than the seller has. Whenever this situation occurs, the buyers pay more.
The ACA is not perfect in making policies identical. (The panels of doctors can still be different.) It, however, collapses many of the distinctions. Aside from the metal levels, some things must be covered by law (contraception, children up to age 26, but other things, too.) This prohibits other distinctions.
With fewer distinctions, companies have more motivation to compete on prices. Then, too, you have all the companies that write policies in your state up there on the same web page in comparable formats.