While there is no clear evidence that gameplay was significantly changed due to Performance Enhancing Drugs (PEDs), the analytics revolution headlined by Moneyball has continued to change the game towards power. Both hitting (hitting fly balls far as the core strategy, accepting increased strikeouts which used to be "embarassing") and pitching ("pitch labs", where the average velocity has significantly increased with harder to hit pitches) were impacted.
Basically, the benefit of a homerun and the benefit of a strikeout were both better understood and so the balance of the game changed so those were more common outcomes.
So the parent comment was referencing the steroid era in the 90s like the sibling comment mentions but you also do still see that in the (presumably) cleaner game today. While upper 90s fastballs used to be rare, they're pretty common now. More and more pitchers are throwing pitches with more and more spin. Personally, I think the game is in a good place especially with the pace of play changes but many (most?) also believe that this arms race, so to speak, is really driving the prevalence of arm injuries. I'm a Rays fan, it's a sore subject this year.
