I absolutely disagree. The company I work at, does.

I also don't agree with the graph showing devops as part of full-stack development. That might be the case in small companies, but most companies will have discrete teams for that. You absolutely can be a junior and be full-stack. Full-stack can be seen as a seniority level like you put it, but many companies don't see it like that. One can have a junior understanding of full-stack. Take for instance Wordpress developers. Like it or not, they are LAMP full-stack. Same goes for MERN, etc.

I also disagree with your suggestion that one should focus on one library. I think no-one should focus on any library, but rather the language it's written in. Become a good JS developer for instance and you can develop in a ton of libraries, frameworks, and stacks. This is called developing a transferrable skillset.