But there was also almost zero holding of shield, ever. The only cases I saw were brief and involved platform play against an aerial opponent.I assume you're only counting shields on which attacks actually landed. In that event, this analysis elides consideration of the times where the blocker didn't get attacked. In other words, it's not just the act of blocking an attack that has been altered by this patch... it's the threat imposed by shield, which prevented poorly spaced attacks all by itself before. Now you can misspace some attacks pretty significantly and often come off clean unless you eat a powershield. That is a significant change even for top level play.
Basically, instead of looking only at what happened because Nairo hit ZeRo's shield, look also at what Nairo had to do because ZeRo was holding shield.
There's no zen philosophy here. The only shield inputs either player was making were instantly released, simple attempts to powershield.