Yes, I know that Mayo Rochester does take some Medicare Advantage plans, I believe there were some special negotiations for that...I recall the discussion on TV and hearing that in Minnesota it is hard to sell a Medicare Advantage plan if Mayo not included.
Your happy friends are merely lucky and the exception because they live close to Mayo. And as I mentioned, many other providers are dropping Advantage plans. Including in the Twin Cities. Once dropped, or if one then wants to go to traditional Medicare, finding a new plan is a problem. Because plans are no longer required to take you like in the beginning. So if you have preexisting problems, they can refuse you.
It is a disservice to not explain the negative reality of the Advantage Plans.

My comments were based on financial analysis. Medicare Advantage plans are not to the advantage of enrollees. They are insurance companies and are profit driven. To make a profit (and pay extra sales and marketing costs, CEO bonus etc.) yet offer a cheaper premium. something must give. Just read their financial statements! Those sales and marketing costs and required profit margin easily add 30% cost to medical care. Yet Advantage plans promise more benefits and lower premiums. And that is why they require approval for tests and procedures, set up their own network of doctors who take less and require copays. That is why there are so many complaints and Congress is investigating Advantage plans. I recall when I went on Medicare reading that Medicare pays out 90 cents on the dollar in services, while my Medigap plan brochure said it pays out 67 cents on the dollar in services. Guess why the difference???? I did a comparison and if I had had an Advantage plan with my medical problems, apart from not being able to self-refer to Mayo, the actual costs of copays etc. in an Advantage plan would have cost me far more than my expensive Medigap plan.
I have seen some heart-breaking stories on Connect of people waiting to get a PET approved by their plan and not getting treated! Pigs cannot fly.