I am guessing that because CentOS releases only every 3-5 years, people forget how much work is done at the beginning of every release. First there is a lack of packages available. Then there is the complaining that the OS is useless because it doesn't have ABC. Then there is finding the people who are challenged enough by the lack of packages to go learn how to package up stuff and make it available. Then there is a section where packages get uniform and together. Then things pretty much stay at that until the next CentOS major release... people either decide they want to skip to the next or just wait it out.
So currently we are in the finding out the lack of packages and the complaining stage. The real challenge will be finding the people who see that as a challenge versus a show-stopper and do the next steps.
Surely this is exactly what the SIGs and CentOS Stream are for: developing and contributing to the forthcoming releases of RHEL/CentOS. If Mate or whatever is so important to you, then get involved in the relevant SIG - which in this case is probably
https://wiki.centos.org/SpecialInterestGroup/AlternativeDesktop
personally, and I know this seems a bit heretic around here, but I actually like Gnome.
P.