Always found the concept of "code coverage" to be a weird phrasing of what's actually happening.

The whole point is to answer the question: do your unit tests walk all possible paths in your code?

Now, the whole point of unit tests is to verify code behavior. See if it remains consistent if you change something somewhere, that kind of stuff. Don't want the new hire to make a well-intended change that ends up breaking things. This is why unit-tests exist. Amongst other things.

One may well write tests such that all possible code paths are checked... doesn't mean the actual code is performant or written in a clear manner, or written in a maintainable manner, etc...

I guess a better term would be "behavior coverage" or something?