Executing PHP on post/pages without plugin

I doubt it, too much risk that an end user could accidentally break something. And it can just cause confusion, that’s why most good plugins these days come with widgets, or have a short code that can be added to posts and pages to avoid messing with PHP functions.

But that being said, I do tend to use a lot of extra PHP myself when building sites, but I try to keep it behind the scenes in a page template or widget where less technical users won’t trip over it 🙂