Yeah people repeat advice like this but have no idea it makes no difference and even in search it defaults to "Apple Music" but shows no results even when that slider is turned off.

It used to work in the first few versions of Music.app but broke about 2 years ago and has never fully disabled it ever since.

You’re wrong. It displays Apple Music, then when you search it only pulls data from what it has access to, which are the free radio stations inside Apple Music.