This advice applies mostly to pop music that involves outside songwriters, marketing, and publishing music, etc. and I agree, the music industry has a tight grip on that sort of “music”. But there is plenty of room for niche products for bands that actually write their own music (ya know, real musicians not dancing, lip syncing performers). Any band can find a producer to work with without a record label and there are plenty of examples of highly successful bands releasing their own albums.