For most people accustomed to group or personal plans in the “under age 65” market, dealing with provider networks is an ongoing concern. PPO or POS or HMO? This concern is no different for those shopping for a Medicare Advantage plan. These plans are “network driven”.
For people who do not want to worry about provider network restrictions (and don’t mind paying more premium dollars), then a Medicare Supplement (Medigap) plan is the preferable choice.