I don't recall Apple ever "insisting" anything about glossy vs. matte. They simply eliminated the matte option without comment, and finally brought it back many years later.
If you have a reference to a public statement from Apple defending the elimination of the matte option, I'd like to see it.
To be clear, I've been complaining about glossy Macs ever since matte was eliminated, and I too purchased an M4 MacBook Pro soon after it was available.
> “…the MacBook provides incredibly crisp images with richer colors, deeper blacks and significantly greater contrast…”
This is positioning for glossy being superior.
https://www.apple.com/newsroom/2006/05/16Apple-Unveils-New-M...
A sentence in a PR that highlights an indisputable advantage of a glossy display does not position glossy as being superior overall but merely superior in the respects mentioned, which is not controversial.
Moreover, Apple continued to offer a matte display in the MacBook Pro for years after that PR, so why would they sell an "inferior" option?