Ask HN: Why do so few tools import data from their competitors?

Let's consider Bluesky for example. When you sign up there, your timeline is empty. But many people are switching to Bluesky from a platform like X.

It would be super simple for Bluesky to add a "Import your X account data", where you log in with X and then it reads out all your profile data (e.g. profile picture, bio, all posts etc.) automatically. Step by step, the users themselves would "reconstruct" X within a technologically more advanced (e.g. federated or peer-to-peer) platform. Not an external tool, but an official importer developed, built-in and promoted by Bluesky.

I've seen the same thing in so many other regards, that there seems to be a strange aversion to importing data from competitors (or it's just not been done), even though it would improve usability and ease of transition to something better soooo much. Why is this?