Why's that a problem? What you're going to be doing on the job is going to change at the exact same rate. But people also tend to talk about recent problems and those may be even a month old. Honestly, the questions are about seeing how the person would approach it. It is not about solving them, because you're going to be doing things you don't know the answers to beforehand anyways.
> It's just that the coding interview is a different interview type
For what reason? "Because"?
The first half of the sentence you're responding to answers this question already. Because you can't compare candidates fairly if you ask everyone a different question. Is a candidate who aced an easy question better or worse than a candidate who struggled with a difficult question?
> For what reason? "Because"?
What are you asking? Why is an interview where you ask about high level design different from an interview where you ask to write code? Isn't that like asking why an apple is different from an orange? They just are, by definition.
In general however, of course, there is/should be a round of interview that covers architecture/system design. It's just that the coding interview is a different interview type, which gives a different kind of signal, which is still important. It doesn't replace architecture interview, it complements it.