If you can’t communicate ideas and basic concepts to non technical people, you will both limit your career opportunities and not be able to get your ideas implemented while someone with worse ideas will.

Developers underestimate the amount of influence you can have just by being able to communicate effectively.

Some engineers really do sit in a quiet room all day writing code, but my experience has been that it is an extremely communication-centric job.

Either way: if you do work in the kind of environment where you need to work with other engs and teams frequently you do need to test communication skills, and simply coding is not always sufficient.

Now, you're right, the technical distillation is not going to be on the level of "explain relational databases to a Joe off the street starting from square one", but it's effectively the same as the skill of "demystifying arbitrary misunderstandings and knowledge gaps other have", which is important.