I totally disagree about the tone and SBS. . Symptom tone is his best . But I agree about that last 2 albums
guitar tone on SBS and Sabotage sound weak vs V4. Like I said, neutered.
Guess you had to be there, hearing the music of the time.
Early to mid 70s was Zep, Deep Purple, Aerosmith, Bad Company, Queen, REO, Journey, AC/DC, Kiss, Nugent, Alice Cooper, Thin Lizzy, Rush...if you listen to the guitar music of the year V4 was released and compare it to the V4 sound, you'll hear how different Sabbath was; and do the same for SBS, Sabotage, etc. and compare what was going on at the same time with other bands, you can't miss it: after V4 Sabbath was trying to sound like everyone else.
With V4, nobody sounded like Sabbath; the closest was Deep Purple In Rock, which predated V4 by two years. If you compare SBS and Sabotage to other guitar bands, you'd hear it too: Sabbath guitars sounded like every other "hard rock" guitar band.
After V4, Sabbath was trying to jump on the mainstream rock bandwagon, I was there in the 70s, and purchased Sabotage, Technical Ecstasy, and Never Say Die when they were first released...and saw the NSD tour in '78 with VH opening.
IMO/IME