I suspect every bespoke web-accessible CMS evolves towards some WordPress conventions over time.
I have built, I don’t know, four (or maybe five depending on your perspective, and not-including small app-specific systems) fairly solid CMSes in the last couple of decades, and installed them in different places, and maintained a few more.
But the ones that have survived the longest are the ones derived from the first, simplest PHP system I produced, which had solid authentication, a very simple page handler model and admin screen model, form handling thanks to a custom version of the legendary fillInFormValues code, etc.
Because it had such simple objectives and structures at the beginning, it has never been difficult to maintain, and it remains incredibly fast.
It is getting on for twenty years old, has gone through two wholesale ORM changes, has a JSON API, is managed with Composer, has CSS inlining support for its transactional emails, etc.
It has also ended up with WP style hooks and actions for the front end, which has allowed me to port my own live SCSS and JS compiler plugins more or less directly from my WP projects.
There is a lot to like about the flat simplicity of the WP hooks and actions model, and the way it can be implemented in other very simple page rendering CMSes. It’s more or less completely independent of plugin initialisation so it’s easy to add it regardless of the scheme in use there.