Not every startup is Google. A lot of companies have CRUD applications of minimal to modest complexity which, even if actively used, are nowhere close to facing performance and scalability barriers that would require deep technical expertise.
These startups don't necessarily need "engineers" with computer science backgrounds, but that's what many of them are searching for.
Sometimes I wonder if it's a case where ego > pragmatism, founders who graduated from top schools, got accepted into top programs (i,e YC), who raised money from top investors, would naturally want "top talent". And it's easy for an inexperienced founder to pursue cargo cult like "google style interviews" when it comes to that.
You hit the nail on the head.
The technical interviews & hiring criteria are often not aligned with what the company fundamentally needs in order to accomplish its goals. The founders/CTO are often rockstars, and they refuse to acknowledge that what their company needs is productive employees, not clones of themselves.
This leads to an enormous amount of time spent interviewing people in search for these rare "unicorns".
Out of curiosity, what makes for a "rockstar" founder or CTO?
I could be wrong but that's my take.
Many times they have built or worked on something technically impressive, that became big & well known (Google Maps, Facebook timeline, Founding engineer at start-up with Billion dollar+ valuation).
If you need to hire somebody you need to be realistic. A while ago it used to be possible to find well above average developers for almost any role, but today the industry is too mature for that sort of thing to happen.
Google alone has 900 recruiters who scour the entire world with an open checkbook for the best talent, while offering some of the highest comp packages in the industry.
Very few software engineering roles actually require "deep" technical expertise. What you describe is pointing out yet another way in which the corporate cliche of "we only hire the best" is so pervasive.
I don't know if there's any credence to that.
It could make sense - even CRUD needs to scale at some point.
Why does every business need to pretend that they are getting the best of the best? Obviously, I want to get there someday, but I'm still early in my career. I know I'm not top-level anything. It would be disingenuous and frankly delusional for me to claim such!