At this point, given all the ACA coverage rules that all plans must adopt to remain in compliance, the only significant distinguishing factors between different plans are costs (premiums, deductibles, co-pays, co-insurance, etc) and network of providers.
In many areas, especially more densely populated areas, the cheapest plans tend to offer unusable narrow networks. Sure, everything is technically covered thanks to ACA regulations, but good luck finding providers in-network.
Networks on marketplace plans are awful in general. For example, in most areas, you’re not likely to find nationwide or out-of-state coverage for comprehensive care (which would allow people to travel to find better or more specialized care if their area doesn’t have it), but many of these bottom-tier plans won’t even cover providers outside of a single region, city, or even just a subset of that city. And of that small geographic subset, they’ll only cover the worst quality providers like underfunded community hospitals. As a result, patients who mistakenly sign up for these plans frequently pay out of pocket for out-of-network care. And since most of these plans are HMOs, they won’t even get any out-of-network benefit asssitance either.
These plans are essentially snake oil plans. Conversely, non-ACA plans are frequently (and justifiably) trashed for boasting a large network of providers, but refusing to actually cover anything. Meanwhile, the reverse is true here where they promise to cover things, but don’t have a satisfactory network of providers to actually provide quality care.
This gets even worse when you factor in how these plans impact subsidies. Subsidies are currently calculated by using the second lowest cost silver plan (SLCP) in your area as a benchmark. If you live in an area that offers these worthless plans, your subsidy will be calculated off those deceptively cheaper premiums, making it so that the more expensive, but actually usable plans still remain unaffordable for most.