What you're saying is that as a website supplier you're more comfortable with the CMS you've written yourself, which is like
duh, obvs!
That's fine too - I use lightweight or self-written frameworks for my own sites that only I deal with, but when I've had a site to hand-off to someone else, using Wordpress means I don't have to explain what I did, and I've found it to have different shitness to the other CMSs I've used. (If there's a good CMS out there, I've not used it.)
Which is not to say there isn't plenty of irritations with WP - I remember menus being a particular pain, and there was a fucking tonne of terrible plugins to navigate through to find a workable gallery, and it could and should be WAY more secure by default.
But there's nothing wrong with software projects focusing on where their skills lie, and using Wordpress (or Drupal/Django/etc) to provide their site.
All of which is nothing to do with the originally asked question:
What do people think about having a federated libre communication platform (like Matrix/Kune/other) for Teh?