Yes a lot of people are building end-user friendly content management system on shiny new tech stacks, and/or paid subscription model.
But let's face reality: Wordpress is powering 43% of the whole web! and still represent 63% of all CMS market shares.
Figures so outstandingly disproportionate means WP is an open-source mature, secure ( if you know how to properly configure it ), easy to host, and up-to-date system, that can rely on an unmatched sized plugin ecosystem.
It's literally everywhere, like PHP everybody told you not to worry about.