If a doctor would today practice medicine the exact way it was practiced in 1950 I don't think you would say that the doctor practices mainstream medicine.

If you define "mainstream" by the amount of people who use it than homeopathy is probably "mainstream medicine". Even if you go by the status of the people, when the Queen uses homeopathy it's no low status treatment.

There are two reasons why homeopathy gets classified as "alternative medicine".

(1) It's uses a ideological framework that goes against the reductionist world view.

(2) There's are not enough high quality double blind studies to allow an institution such as cochrane to recommend homeopathy as a treatment.

The term Evidence-Based medicine got made up by a bunch of university professors in 1992 to describe the style of medicine that they were teaching. At the beginning the term intentionally downplayed clinicial experience. Today most medicial schools say that they teach Evidence-Based medicine but they weakened the definition in a way that allows clinicians using their clinical experience but that still focuses on peer reviewed trials.

If you don't pracitice medicine the way the university teach it in their normal programs than you are practicing in my opinion "alternative medicine".