Actually there were about 10 pitchers with an ERA below 2.2, so “at or around 2”.
Gibson was “at or around” 1.0.
Big difference.
Yes, 1968 was the Year of the Pitcher, but unfairly or not(and there is MUCH that is unfair about the way baseball history is retold...ahem...ridiculous and unfair east coast team and player emphasis..), the bellwhether of that group was clearly Bob Gibson, and many sources cite his off the charts dominance as triggering the rules change.
Here is one:
http://www.baseball-statistics.com/HOF/Gibson-Bob.html
Sooner or later, Bonds would have gotten tired of eating dirt, or having bruised ribs.
There were a lot of pitchers back then who wouldn't have put up with that crap, but that wasn't the Bud Selig era.