Who said anything about HTML and CSS?
Apps like VS Code create and manipulate a DOM directly in JS, or more often these days, WASM. To these apps, Electron is just a virtual machine with a lot of browser-like multimedia APIs attached. You pin the exact version of the renderer just like you pin the exact version of your dependencies in a server-side app, or the exact version of the OS in a virtual-appliance VM image.
Electron has nothing to do with "the web" or "web standards" other than borrowing technologies originally developed for those. Electron competes with things like Unity and https://love2d.org/, not with browsers. It's in a category of frameworks with the goal of giving the developer pixel-perfect control over what the user sees, where apps are separately developed, tested, and tweaked, for each target (e.g. each OS, each kind of display/interaction methodology, etc.)
With this category of framework, you don't build your app as generic code targeting a standard; rather, you build, and test, your product against a specific "engine." (Imagine for a moment that people could take Unity apps and run them against any old version of the Unity engine, or even against Amazon's Lumberyard fork of the same. Would anything work?)
in much the same that sharpened sticks compete with power tools, yes
Similarly, if your goal is drawing the views of a CRUD app, any tool you use is going to be used as a glorified version of Display Postscript.
> 1. this would lose you the ability to develop for a particular version of the renderer
html and css are standards, if you are developing for a version, you are wrong. full stop.
> 2. this wouldn’t give you the benefit of Electron sharing service-memory with Chrome itself
there would be no electron so point is irrelevant