The truth is, 1st-party apps are well-supported but 3rd-party SDKs provided by these companies, especially the ones don't generate revenues (Facebook SDK, and many others) are simply not well-supported within the organization. They are not dogfooded, they don't develop with the latest and greatest tools available for 1st-party apps, some of them have very spotty CI, and often their release schedule is not as rigorous (many 1st party apps adopted weekly release schedule).
I would disagree that the 3rd-party SDKs don't make revenue for Facebook. They likely provide additional targeting and behavioral data that feeds into their giant ad machine and lookalike audiences.
