I think it’s bad that there are Angular developers who do not know JavaScript. Of course you don’t need to deeply understand the latter to make progress with the former, but the result will be a team that outputs potentially inefficient and bloated software, especially if, specifically to your example, they’re also using Bootstrap for styling.

Software development would be much better with more developers who are actually experts, or at least intermediately-skilled, in a particular specialisation. I would never let a manager touch my codebase unless they were also a seasoned developer, because I can guarantee that they will write a bunch of unmaintainable crap.