From the parts I've seen (Foundry et al), the promise is ability to sense of data and controlling its stocks and flows. There is a bit of Pachyderm-like versioned pipelines, notebooks, lots of access controls and audit logging. This is a place that was bought into Oracle "data democracy", reluctantly used Foundry and then was won over by the product.
Just kind of summarizing from the comments in this topic (I also couldn’t be bothered to Google Palantir’s thesis): sticky/useful tools to combine and enrich data sources with a focus on a sector where there is a lot of compliance-driven security, data sources that aren’t easily queryable outside of their direct users, and high barriers to entry.