[jinushaun]

But 10-15 years experience has to count for something. Why do senior and principle positions still need to leet code interviews?

[Salmonfisher11]

Because there are a lot of fraudsters.

With social skills and salesmanship, you can never have delivered top-class work even after 15 years as a developer.

Quite a few people know how to "play the game". That's pretty easy if your superiors have no idea about software development themselves.