I've heard this as well. They essentially hire customer-facing engineers to go out and scope specific contracts and literally implement custom solutions with small generic software frameworks they developed in house.
On the other hand, the customer has results after 6-8 weeks. How much software can really be built in that sort of time frame? Not much...
In my opinion Palantir is a product company, but the product is deeply integrated in to an enterprise. And doing that takes time and people.
I don't see how you can simplify that into calling it a "dev framework".
Fair enough. But you may be underestimating the value of production-quality fast-development dev frameworks in enterprise.
Remember, these are guys who are used to seeing 5-year project timelines for anything that touches more than one system. (And every business case touches more than one system...)
One other thing to note is that while they build these custom solutions, the second you touch their stuff that support policy goes out the window, not unlike what Oracle does.
EDIT: n/m @dang answered this indirectly a couple of comments below.