I was plenty old enough, but didn't even hear my first recording by them until the mid '70's. Somehow I ended up with a copy of Paranoid.
The stations I listened to were still the holdovers from the newer, free-form FM stations that emerged in the '60's, and I think that they considered much of this type of music, "bad vibe music"
They may have had a point "Black Sabbath" certainly doesn't conjure up visions of peace. love, and understanding, the message of "War Pigs" notwithstanding.
Frankly, I always dismissed this genre as juvenile, (and though I can get with rock at at it's most basic), rather unsophisticated musically.
The fact that Paranoid itself was reportedly written in less than a half hour as filler for the album may bear this out.
That said, I have been known to spin this disc with the amps set at relatively high volumes