Well, it is very simple: Linux expert users do not represent the user base that RHEL is interested in.

RHEL is interested about that one guy or woman that actually decides(to pay them) and has control of the company. This person wants control overall of what people do with (her company) computers.

Desktops like Gnome have a very limited set of options, great for companies. More stable, less problems, people focusing more on work to do at the company.

I used to program KDE widgets for things like displaying the tides, the lunar phases, sunset times and so on. It was a cool thing to do and useful if I wanted to go fishing or to the beach. Marginally useful for work.

Working you need something that works, with the least amount of work and money possible. KDE is not designed for that.