Thanks! Fascinated by life pre-Metallica, and how Sabbath must have stood out like a sore thumb in the musical landscape.
I think no matter what, people will call certain songs 'filler' depending on their familiarity with the albums. But with bands as huge as Sabbath or Metallica, every song will find an audience.
I think among Sabbath or Metallica diehards there is no such thing as filler, your right. But I think when the average person buys these albums (well...not Paranoid...that thing is flawless), but I could see many casual fans thinking much of Load and Reload are filler between the hits they know. Even if I don't think so.
Thanks so much for reading!