Having a set of common knowledge to interview about is in fact very useful.

It's like a dance. Your are supposed to lead deriving the solution, interviewer is supposed to follow closely and judge your performance.

If you expect to ace an interview just like that then you also need to be lucky not accidentally getting asked to stuff, which you always need to Google an answer to, basic algorithms and patterns, which you usually kind of know but could slow you down during the precious 40 minutes you have to show off your skills.

And lastly, people do prepare for these. If you do not do that, you might simply make a slightly worse impression than someone who did.

That being said, I mostly did not prepare for the coding interviews. I focused on the design and behavioral interviews.

At FAANG, most people are not doing any of these things. Think of people working on EC2, Ads or Maps.

I only worked at multiple FAANG and I never had to design a database schema or make data available via API.

It's not hard to do those.

And I suppose for most business cases out there, writing data to the DB and reading it back later is all it takes.

However, there's plenty of other problems where the skillset you mentioned falls short.

For instance, you talked about designing a database schema. Do you know how to design and build a database itself from the ground up? What if that DB has to be distributed, with thousands of writers? How do you ensure consistency and consensus? (These are all solved problems).

Think about Linux kernel developers. Do you think DB schema design is an especially relevant skill for them to have?

Can you come up with a compiler, or your own programming language?

Try building your own text editor, with features like syntax highlighting, undo/redo etc (it takes clever algorithms).

I'm not claiming I can do all of that; just mentioning that the whole scene is much more interesting beyond the horizon.