We really are bouncing back and forth between flat UIs and beveled UIs. I mean, this is what old X11 programs looked like:
https://www.uninformativ.de/desktop/2025%2D06%2D21%2D%2Dkatriawm%2Dold%2Dxorg%2Dapps.png
Good luck figuring out which of these UI elements are click-able – unless you examine every pixel on the screen.