First, CentOS does not have upgrade from one major version to another. Never had. Always a fresh install.
Second, attempting to install RPM’s from one distro into another will probably create chaos (as packages have dependencies).
Mate desktop for el7 is in EPEL. The maintainer refuses to create Mate for el8.
Admittedly, I have not checked lately. I have CentOS Linux 7 setups, where Mate is in use due to hardware requirements and might continue with el7 as close to June 2024 as possible. There seems to be a chance to skip el8 and move to el9 by that date. We have binary blobs and source-install applications that all have to be ported to platform, so one less porting round sounds nice.
Sorry about the digress. I also belong to the “I don’t care” type of users. I have Gnome 3 in use. I can start applications (terminal is most common) and put them in workspaces. One or two windows per workspace. The rest I don’t care / need. (It is easier than starting X11 without window manager, just xterm – been there, done that too.)
I’ve heard that new (university) students learn Gnome 3 quite easily. I’ve also heard that these younglings, “digi-natives”, are less adept than dinosaurs …
(Naturally, hearsay is not a reliable source.)