Commercial? You were not living those days. Even if they were to appear in some tv show from time to time, that was not what the regular people thought about metal. Metallica was the first big mteal band to do it on the radio, and all because it was promoted by the mainstream media when they released the black album.
Listening to metal in the 80s or 90s was very "underground". People was looking at you as if you were some kind of freak and the most common sentence that you could here regarding music was "I listen to all except for the noisy one".