It’s like teaching someone to read with emoji before getting them started on the alphabet.
I'm a hardliner against CSS frameworks. Any time you learn a CSS framework, you're picking up a tool that is going to break or be made obsolete in a couple years. Just learn CSS right the first time and you're good forever.
That's why CSS frameworks are so popular. I can install bootstrap and make something not terrible pretty quickly. As someone new to programming to do the same in raw HTML and CSS is much much harder.
CSS is like global mutable state — it is too flexible to properly work when multiple people work together on it. Sure, I’m never against learning something from fundamentals, but I am on the opinion that it is increasingly the wrong default.