Complaining that breadth-first-search is irrelevant to frontend dev seems concerning to me. The DOM is a tree; so are JSON structures; so are website directory structures; so are half the data structures you will encounter in most businesses (departments, categories, etc.). You WILL need to traverse a tree in a frontend position at some point. I absolutely want to know whether a frontend developer has a variety of tools in their toolbox for handling tree structured data - and ideally the ability to refactor between recursion (using the call stack), explicit stack descent (which will be depth first), and queue based descent (which will be breadth first).

I think that's an unfounded and problematic stance.

Front-ends almost always involve working with data. It is increasingly common for front-ends to have filters, searching, sorting, etc... of that data as well.

Doing that efficiently is key to ensuring a fast, responsive UI.

Wrangling with divs and CSS may take a disproportionately large amount of your time but that doesn't mean it's the most important skill to look for, nor does it mean the CS questions are somehow irrelevant to the work.

Of course they're unrelated. The interviewer asking this doesn't expect you to write these algorithms all day, they want to know that you have the basic mental dexterity to figure things like this out. They are, ideally, abstracted problems of the complexity that you'd be expected to be able to solve on your own.

There are some positions where you don't have to care if people can really problem-solve; as long as they can tweak CSS until it works right-ish, or know the particular arcane implementation details of installing some WordPress module, they can do the job. But there are a lot more positions where you want someone who can solve the problems that need solving, pick up new technologies as needed, and just generally be a flexible and productive contributor in a way that doesn't relate to the fiddly details of one particular technology.