I think it all started with the really, really strange change in which Audio Technica placed its Shibata cut as something superior to the ML cut. Previously, mainly in the 80s, the ML cut was the top stylus option with the biggest price.
I think this might have something to do with Ortofon doing the same thing before Audio-Technica: i can recall that somewhere in the 2010s Ortofon issued an MC cartridge with Shibata cut, something that was completely strange/unheard of for Ortofon.
So some marketing genius figured out that the public perception was going to steer into "Shibata = Best" soon.
I don't understand why you say 7um is quite large. 7 micrometers is about 0.27mil, thus more or less equivalent in high frequency capability to a 0.3x0.7mil ellptical. Can't say this is "quite large" when these are the dimensions of some very good ellptical styli.
To illustrate Cafe Latte's point (pun intended):
US Patent 3774918 to Norio Shibata:
View attachment 3080842
The shibata is done by doing two back cuts to a regular stylus. Obviously the goal was to keep the stylus manufacturing as simple as possible. The patent even mentions a Shibata stylus done by adding only one cut (!) instead of two. Here the cost reduction is hinted at:
View attachment 3080852
However the patent hints that the sharp edges are to be rounded off:
View attachment 3080858
View attachment 3080859
... so in theory there shouldn't be sharp edges there.
Now, i am not contradicting your claim that after 100h the Shibata has changed in shape; i'm just adding some precisions.
Norio Shibata, born in Aichi, Japan, graduated from Yamagata University in 1964, invented the Shibata stylus in 1971.
He must be turning in his grave now...
But THANK YOU Norio, thanks to you we went beyond the elliptical!