At most of the companies I’ve interviewed at (except Google as you note), the hiring manager and principal engineer didn’t understand system design themselves. They only understood how to pattern match against a regurgitated answer.
Case in point, when asked how I’d build Slack, I spent most of the time on data persistence because slack stores all data forever even on the free plan. I got rejected because, “we don’t care how they store data.”
Ok, but that’s still a key part of the system design…
Of course, it was a conversation and the engineer was happy to let me go in depth on storage after we discussed and dismissed other areas, like the front end, integrations, native apps which were not related to infrastructure.
We also covered other areas like messaging, authentication, authorization, read / write paths, etc… so it was very strange to get the response from the senior manager I got.
Case in point, when asked how I’d build Slack, I spent most of the time on data persistence because slack stores all data forever even on the free plan. I got rejected because, “we don’t care how they store data.”
Ok, but that’s still a key part of the system design…