KDE 1.x in particular took a lot of influence from CDE. See the design of the taskbar, virtual desktop switcher, window decorations, scrollbars etc in these screenshots: https://en.wikipedia.org/wiki/K_Desktop_Environment_1
This is the reason behind all the s/C/K naming substitutions within the KDE ecosystem!
The race to customizability & the notion that GUI correspondence could win some Win9x fence sitters over, really did it big time for future Gnome & KDE.