Can you imagine how many great pitching performances we are missing. By todays standards we would have missed one of the greatest pitching performance of all time.
On the one hand I agree with you, but on the other hand, I would say that the game has changed enough that it's unfair to measure.
On a very simplistic level - ERA is not as meaningful as it was when pitchers completed 50,60,70% of their starts. Heck, they barely get through 7 innings.
And strike out rates are bloated when many batters are in HR or Strikeout mode