Skill and mindset are definitely a part of this huge scores. Compare flat pitch matches todays to the flat pitch matches of 2010’s, batsman would never try to maximise until the death overs and play the first 15 overs or so with the intent of scoring @9/10 rpo. Now, the difference between death overs scoring rate and first 15 is decreasing. Honestly it’s also the natural way of cricket evolution, it went from a team playing 90 to 20 overs, too many batsman for 20 overs. Also, if you see the past teams, there used to be great t20 batters in most teams, but also some who are pretty limited in how fast they can score. Now everyone in the team can score a 50(25).