You can get away with sloppy, cluttered and inconsistent UI on mobile when everything runs serially, full-screen.
But bring that to desktop, where your UI is windowed and appears alongside (or overlapping) other windows, and you end up with chaos.
The floating sidebars are a prime example of this. Why should I have to expend mental energy to differentiate what's an actual window -vs- what's just a novelty round-rect with a shadow (oh, and and window controls for the parent round-rect, which is a window)?
But bring that to desktop, where your UI is windowed and appears alongside (or overlapping) other windows, and you end up with chaos.
The floating sidebars are a prime example of this. Why should I have to expend mental energy to differentiate what's an actual window -vs- what's just a novelty round-rect with a shadow (oh, and and window controls for the parent round-rect, which is a window)?