Please explain to me what it does that xfce does not and why you need it?

The whole point of linux is that it's supposed to be efficient and from what I have seen KDE eats up twice the memory and CPU power without providing much additional useful functionality.

And no, using my file explorer as browser is not usefully functionality when full fledged browsers exist.

Always remember the UNIX philosophy: Do one thing and do it well.
Also, death to systemD.