These year-old posts from Piotr Solnica are about Ruby On Rails ...
... but the experiences related therein should be valuable to anyone using or building a full-stack PHP framework. (I can imagine it applying to CMSes as well.)
Does this story from Piotr remind you of any framework-based project you've worked on in PHP?
Once, I joined an existing project. It was a huuuuge app which was running an on-line shopping community website. Complicated sales model, complicated promotions, complicated product setups, coupons, user groups, messages - it had it all. I joined them to help ship a few new features. One of my early tasks was to ... add a link to something on some page. It took me few days to add this stupid link. Why? The app was a big ball of complex domain logic scattered across multiple layers with view templates so complicated, it wasn’t even simple to find the right template where the link was supposed to be added. Since I needed some data in order to create that link, it wasn’t obvious how I should get it. There was a lack of internal application APIs and relying on ActiveRecord exclusively made it extremely difficult.
I've consulted on projects like that more than once. Indeed, the posts might well have been subtitled "The Perils of Convenience-Oriented Development":
People are attracted by Rails because it gives you a false sense of simplicity, whereas what really happens is that complexity is being hidden by convenient interfaces.
Read both of the posts, and see if you can relate. They just reinforce to me that this is what to expect when you embed your domain logic in your user interface logic.
Remember: with server-side web-based applications, the user interface is the HTTP request and response. Any code that reads from the request, or that writes to the response, is part of the user interface. Putting your domain logic in the user interface is convenient to start with, but as soon as things become even a little bit complex, that "convenience" becomes a burden.