My understanding is that Palantir is running an engineering mill/sweatshop using fresh out of school CS grads (particularly from Stanford). That much of their time is spent simply writing client-specific code that imports and cleans up data from disparate enterprise systems. That its not challenging, innovating, or exciting. Of course this is all anecdotal based on what I've heard from friends and a Palantir engineer…
Note that that work doesn't require a top CS degree. Palantir could easily achieve 97% of their results with tier 2 grads, but because they only take Stanford/Princeton/MIT/etc, they can justify their high prices to clients. It's classic consulting - McKinsey/Bain/BCG could achieve 97% of their results with tier 2 grads instead of Harvard/Wharton grads at lower salaries, but you gotta wow the clients to win the jobs.
Do we actually have any data on Palantir's hiring practices? Because my personal anecdata is that I have a friend working there and he's from a tier 2 school (University of Toronto, maybe even tier 3?).