hmmm those are good points and I actually agree with a lot of what you said, but I think you could also flip the scenario just as easy. For example, in practice, my serves are almost always low and spinny. In a match, when the mental aspect comes into play, I tend to make more errors on my serve (serving high, or not as spinny, or not in the exact place I want). For serving, it definitely has to be mental because it's not like my opponent is giving me a quality ball and throwing me out of position, you're literally starting the point.
But once the point has started, it's different. Is your inconsistency due to bad technique? quality of opponents ball? bad mental game? Seems like there's a lot of nuance.
I do agree though that at my level, most of my problems are still from technical or movement inconsistencies that could be improved.
I still would assume that at a certain high level, the mental aspect takes a front seat. Like in the NBA, all of those guys are physical FREAKS, tall, fast, perfect shooting motion. However, There are players that are levels above other plays when it comes to shooting daggers when the game is on the line. Kobe wasn't physically levels above other NBA players but he had the most supreme mental game. Drew Brees was definitely not the most physically gifted QB, but his mental game was solid gold.
Even taking it back to table tennis, Ma Long was still winning many matches, even after his physicality diminished because he was strong mentally (WQC on the flip side?). Of course, talking about pros is not the same comparison as us HOBBY players lol.