It's generally regarded as stupid to spend a bunch of time writing your own CMS. It's the website equivalent of spending hours fiddling with your vi config. Or the software equivalent of sorting your record collection in biographical order.
Heck, I know folks who work on WordPress. They are nice people and they are doing their hardest to work around the troubles of WordPress past and I don't want to slight them.
I've been working since 2014 quite seriously on getting a new version of my CMS, pretty much written from scratch, together. And it's finally actually functional and rolled out. With a new audio player, improved better-looking score display, etc.
Now I have to spend some time writing some music. :P