This idea doesn't necessarily hold up when you get into very deep topics like data science, db admin, cloud administration, server admin, etc. But it absolutely holds up for product development, and nearly all frontend, backend, and "modern devops" should actually be called by its real name: full stack development, or my preferred term, Product Engineering.
I view every single product-focused engineer we hire as "full stack with a focus". The job titles might say things like "frontend engineer" for SEO, but the descriptions are clear: you're going to mostly be working on frontend and we expect competency in that, but you might be asked to reach into other parts of the codebase, or at least have opinions on how things are designed there. You'll be asked to participate in product planning and design. Everyone is general, but you do have a focus which represents 80% of your work.
I know coding schools would love to just teach someone React and then the bare minimum of a NodeJS backend to check a box then say they're competent. Bad news: I've worked with a dozen coding school grads over my career, as well as a dozen people who classified themselves as "backend engineers". None of them were even playing the same game as the people who took the extra time to expose themselves to the entire spectrum of technology a modern product might use. Mind you, many of these fullstack people were CS grads, many others were just people with no formal training. Formal training only matters if you limit yourself by how you've been trained, and then it matters in a negative sense.