Are you talking about persistent "notifications" that stay in the notification list and can show for example media controls? I think for media players using certain (cross-desktop) APIs it can do that automatically, but other apps would need to have that feature added specifically as far as I'm aware.

I don't dislike GNOME and in isolation, it's probably more forward-thinking and sometimes even makes more sense than KDE. But the reality is that most applications don't specifically cater to GNOME, including the ones I've listed. Even Valve, which invests a lot into supporting Linux, doesn't specifically support GNOME with Steam. If you close all Steam windows, Steam is apparently gone (but it's obviously still running). I'm not even sure if it still shows up in the "dock" as running that way?

I think GNOME's philosophy of not adding every feature anybody could want to have is good. They are clearly focused on their vision and leave the rest to extensions via an API that breaks compatibility rather often, but is otherwise very extensive.

But my point still stands: for a beginner coming from Windows - which is what I assume where most Linux beginners come from - KDE feels more at home, matching pretty much everything Windows Explorer (or whatever you want to call that desktop environment) does: there is a task bar that by default pretty much behaves like the Windows taskbar, the tray icons area works in much the same way, you can minimize windows, the start menu offers search and a list of applications etc. What you already know from Windows will get you quite far in KDE. It then adds a ton of configurable functionality on top and that's where it gets more complicated, but most users (especially beginners) won't even want to fiddle around with this stuff.

If we're talking about a beginner as being someone who is new to computing in general: well, take your pick.