I still slip <?php> tags straight into inline html a la 2004 from time to time, when it suits the purpose. I even occasionally use href="javascript:" if it saves time. No shame in using what works.
templates are always limitations, my friend. albatrosses. You're so right about the awful structure of the big CMSs...
I've just used my own RYO CMS for 15+ years for website work... it's gone through lots of updates, but it's super simple. I'd never make it public as a framework because any decent dev should be able to roll their own anyway, and I don't need the aggravation. But it's basically a VERY simplified cross between {{handlebars}} and React, without attempting to bind the whole DOM to data, plus a DSL for specifying all the pages and modules of each website in SQL, and setting up english-language router rules.
I'd ditch ergonomics any day for understanding what's going on and being able to pare it down as much as possible. Simple website clients pay so little these days it's basically charity work... you need something you can both do in an hour AND never have to worry about WordPress updating.
At least in Python, that's kinda what https://www.makotemplates.org is. Although if you're just using a subset of PHP suitable for templating, it's not really clear to me what benefit there is to PHP syntax versus, say, Jinja2 syntax.
the whole thing with PHP, originally, was you just wrote HTML pages and slipped in PHP <? echo $hello; ?> code here and there where you wanted the server to fill something in with server-side processing as the page was served. This is how it was used before it became common to generate whole templates or pages out of code. You'd be serving a basically static webpage and have a counter at the bottom showing hits, for example, so you'd take your .html and rename it to .php and the counter would be tagged to be generated by the server but everything else would just be plain HTML. PHP still supports this and the fact that it evolved into a full fledged language where you generate HTML from it (as opposed to embedding its output in static pages) still seems slightly humorous to me.
PHP with a correctly-configured server is about as fast as web-oriented scripting languages get, in practice. Yes, including Node. To be sure to beat it you'll need to switch to something compiled, and then take great care not to make any mis-steps.
If I'm in a hurry I still just use the fucking <center> tag. It works and I can't be bothered to google what's correct this week, if I'm just dipping into HTML for a minute or two.