> Please read the letter all the way to the end. This is aimed at distributions breaking apps by default, not tinkerers playing with their own setup.
The only reason why people care so much for their apps' "branding" is being enforced by product management. Absent that pressure, you get a reversion to the Windows ecosystem pre-2005 (more or less), where every user can make their desktop as nice or ugly as they want, and by and large, the sky isn't falling. Because everyone works with the platform and tries to fit into it instead of breaking the mold.
Again, this letter isn't about users making their desktop nice or ugly; it's about distros applying stylesheets to apps without checking whether the app remains usable, and leading users to expect that this is the app developer's responsibility.
As a user, theming is a powerful feature to make things look somewhat consistent.
Though I use KDE and Qt apps as preference, and very few gnome apps. They tend to cope with this pretty well.
So for me the comparison against KDE is very different. KDE's tools have pretty sane defaults and can be customised very well.
They say that they're not against tinkerers but that's exactly what they've done with libadwaita and libgranite.
They refuse to play nice around theming, user-selected icons, security sandboxes, disabling of tracking functions, providing security updates. Many are careless around the amount of memory or CPU used.
Distributions, instead, are on the side of the end users.