HTML, CSS and Javascript do not require ANY use of terminal, commands or package managers, or even knowing those things exist.
The designer who wants to code can learn and develop locally all day long without touching terminals or package managers, or any of that boring lifeless crap that will drive them away.
If the designer who wants to code wishes to version control, they could use Github Desktop or other similar non-terminal applications. You can push and pull all day long without touching a terminal. Github Desktop is a nice, lightweight application that works well and is easy and reliabe. I use if often.
An example: The designer who wants to code may decide they want to make an interactive animation. This means they are about to embark on a journey of HTML DOM, CSS, and javascript. It DOES NOT mean they are embarking on a journey of typing a bunch of distracting non-code into a lifeless terminal. Forget about that. Focus on code - HTML, CSS, JS.
> "They all required a developer to push up a staging environement"
Oh no! How dare they!
If the developer hasn't made a staging environment, I'd be asking why not. It's not hard, and is appreciated for sending preview links to internal non-technical colleagues or clients who wish to see progress or specific features. Staging environments are a very good idea, are you suggesting they are not?