Well, maybe they weren't 'rampant' whe Mike played, but they were definitely "around". They have been since the 50's at least. Ahnold, the Terminator, was using them heavily in the 60's.
Maybe, you now have a reason to doubt.
Schmidt's stats, as I recall, show a relatively steady career in terms of home runs and batting average. I suspect the guys who have that big spike in numbers for a couple of years, then devolve into injury plagued years after that. If Schmidt did the juice, he was consistent with it over a 15 year period. Seems highly unlikely.
Well, steroids have been "around" since the 1940's when testosterone was used on Nazi soldiers. The invention of Dianabol came soon after that.
But steroids infiltrated different sports at different times. Bodybuilders first in the 1950's, then the NFL and track in the 1970's, then everyone else in the 1980's. Baseball lagged far behind in its understanding not just of illegal steroids but general strength and conditioning principles to begin with. So I really doubt that anybody's records up through the mid-1980's are suspect.
BTW, I love your screen name! A Grail??!!