When every new website on the internet has perfect, semantic, accessible HTML and exceptionally executed, accessible CSS that works on every device and browser, then you can tell me that these languages are not valuable on their own. Until then we need to stop devaluing CSS and HTML.
I could probably boil all of this down to “Don’t be a jerk.” But “Learn HTML and CSS” is the one thing that the accessibility community has been saying for years and years and years and years, and if we were to turn this into a drinking game, (every time you have to correct some developer’s HTML or CSS, take a drink), we’d all be dead from alcohol poisoning. And it’s incredibly disheartening to ponder where we might be if everyone who ever built anything for the web had learned its foundational technologies properly. So, go learn HTML and CSS deeply, and quit devaluing these technologies by your words and actions.