“A terrible guide to the terrible terminology of U.S. Health Insurance” by Brian David Gilbert
HMO - health maintenance organization. It's a type of insurance where you have to get referrals from someone you designate as your primary care provider.
PPO - preferred provider organization. Another type of insurance where some providers are "preferred providers" who partner with the insurance company to offer reduced rates. You don't need a referral to see a specialist, but many specialists won't see you without a referral anyway.
I have no idea what a "PPO doctor" is, I've never heard of a doctor that only accepts PPOs, that's ridiculous. I guess if a referral is required then the nebulous "they" won't refer you to the "good" ones if you have an HMO?? Except, in practice, you end up at the same handful of providers in your area no matter your insurance. I've had both HMOs and PPOs throughout the years, same shitty doctors on both.
This is very dependent on where you live and the density of providers. If you live in a small-to-medium size city or smaller, your description is accurate. In big cities, it's not; there is a whole set of doctors who don't work with HMOs at all, because they don't have to. They often are the best, most in demand doctors as well.
Edit: Kaiser is non profit. There are HMOs which exist primarily as cost control organizations, not primarily committed to health care, so experienced vary
Here in the US, you can get surprise medical bills greater than $10k USD, due to these organizations saying "nope, not gonna pay for that."
While in some cases, homeotherapy, and similar, this is justified ... in many/most cases, it really isn't. HMO/PPO etc are all about reducing cost of the care, with these organizations funding themselves from driving down the cost of the the service.
Doctors have to hire people to handle dealing with the insurance companies (HMO/PPO/etc.) Its expensive and time consuming to deal with them.
I guess this depends on your situation. I've been in and out of doctors my entire life. The doctors that give a damn are generally locked away from you if you're using some sort of state health plan or HMO. I have only ever had luck finding a good doctor by going through PPO. If you can do this, I would recommend it. PPO doctors make far, far more (because it's expensive even to you) but the specialist access is second to none. It took 3 months to get an appointment with an ENT once, and when I switched to PPO my GP had me into an ENT at my request the next week. Then you start the cycle of feeling them out and finding out which ones mesh with your goals.
It's tough, but navigating healthcare is tough. Just avoid HMO insurance and you'll do a lot better (or at least better than baseline).