In your example, if bluesky goes you lose it all (until/if their form of federation actually exists and is usable). If the Mastodon server I’m on (toot.community, because I like the name) goes, you move to another or host your own and keep on trucking.
When reddit did their API shit i left and lost the account, subreddits, apps, everything. When Lemm.ee announced it’s shutdown i moved to lemmy.zip and picked up exactly where I left off.
They all have 2 factor authentication too. Sometimes I just want to be in another room than my god damn phone.
Focus on users as well. Not that many people care enough to come post articles on here about Trump or whatever.