The problem here is really that people with great marital relations don't really disclose, because the details are private, so short of some peripheral advice, that voice is absent from the public square.

On the other hand, the people who do talk openly about their sex life in detail tend to be weirdos. So I'm not surprised the opinion is unpopular amongst the degenerates who rarely hear good advice and can't otherwise figure it out due to severe mental defects.