I don't think we need to be this dogmatic. While I do most of my social media on Lemmy and Mastodon, I occasionally look at Insta and Bluesky (which I consider not fully federated yet). The two platforms I've left completely are reddit (API changes, terrible first-party app) and Twitter (son of South African emerald miners). I think federated services will win in the long run but we don't need to be pure users in the meantime. You go where you can still hold your nose.