What you’re talking about is semantics. At a base level, whether you use a templating engine, include / require, or just straight up mix HTML / PHP - PHP “stops execution” to output to the browser.

Templating engines are cool, and they make it easier to separate your views from logic, it makes interloping more straight-forward and possibly more maintainable, but I do not agree that it’s defacto. I think the strength of PHP is it’s ease to just jump into it and get something working, right “out of the box”. The ease of mixing PHP and HTML is a boon from an entry level aspect. Easy entry level leads to wider adoption.

I could create a vanilla PHP application that organizes views just as well without a templating engine which could be understood by someone with baseline PHP knowledge - that’s good thing. It’s inherit to PHP and I won’t need to worry about keeping an templating library updated or ported to we new engine.