That’s a very nice theory. Decent real estate first buyer will not even consider rented property. But there are enough unscrupulous shady people who will buy the property at a great discount and get the tenants out. You will be right according the law, but still mistreated. Will you enjoy abuse waiting 3 years for a court? Probably not. It’s not their first rodeo.

most rented property in germany is owned by large firms who make renting out homes their business. for them, that is not an issue. most homes that people buy for themselves are not even available on the rental market. as you say, people who want to buy a home for themselves will not consider rented property. i believe that is true in germany too. if it happens then it is a rare edgecase, and they will be able to find out in advance if the tenant is willing/able to move out.

When you inherit property, it comes however it comes. I've been displaced twice by heirs. A lot of rental houses in the Bay Area are second/empty nests.