But unless that 3rd party code, and those services, have already been discovered, evaluated, and learned by that particular dev team, integrating them might tak

But unless that 3rd party code, and those services, have already been discovered, evaluated, and learned by that particular dev team, integrating them might take more time than building something from scratch that meets the specific requirements at hand. And if it's built in-house, that means that in addition to being much more tailored to the organization's needs, it can be much more easily changed as those needs evolve. This doesn't mean that I think it's always better to roll your own, of course; there are lots of instances where that counts as "reinventing the wheel." But it's absolutely not as simple as "just use something that's already out there and it will be faster and work just as well."