This is true. But. . . . In nine years my wife has had hundreds of thousands of $$$ in medical bills. rehab, hospice. My cost aside from the premium was $0. My time to do paperwork or appeal claims is 0 minutes. The premium cost compared to others was the same or slightly less.
I have no complaints and will not change.
My son had a medical equipment business. He billed medicare, various insurance companies, patients. The fastest pay was UHC.
I don't know how they are as an independent insurance company but as a Medicare supplement with AARP they do a fine job.