>many apps now just use CSD

If there's something I hate about Linux, it's CSD (Client-Side Decorations, in case people don't know what it is).

If I wanted all my apps to look different from each other, I'd use macOS. I want a clean desktop environment, with predictable window frames that are customizable and they all look the same. CSD destroys that.

Having no CSD at all is unacceptable on small screens IMHO, far too much real estate is taken up by a title bar, you can be competitive with SSD by making them really thin, but then they are harder to click on and impossible with touch input. At the moment I have firefox setup with CSD and vertical tabs, only 7% of my vertical real estate is taken up by bars (inc. Gnome), which is pretty good for something that supports this many niceties.

Linux doesn't mean GNOME.

KDE favors server-side decorations.

Conversely, I don't want all of my apps to look identical to each other. I want to be able to tell with a submoment of a glance what app I am working on or looking for without having to cognitively engage to locate it, breaking my state of flow in the process.