"Why would you work at a place that has such a long standing, very tenured network of people that trust each other more than anyone new"

In general, trust and longevity (in addition to a smallish size) are desirable qualities in a technical team of experts.

The product itself signals then the technical merits of the team.

There is the 'expert beginner' idea that it's easy to stagnate and entrench oneself in a dysfunctional organization.

A long lasting team of expert beginners is an antipattern of course.

But the way to get a high quality team is not by churning through hires - it's by successfull hiring.