@therealduckie You bring up a good point here, because that is a risk factor and absolutely something that could potentially happen to someone.
That's why it's a good practice to backup your data from time to time if keeping it long term is important to you, which you can do from the Import / Export link in your Preferences.
There are apparently some technical limitations which make it so you can't import your posts to a new account on a new server, but you can move your followers, block lists, mute lists, domain blocking lists, and bookmarks.
So again, it's a good practice to occasionally back these things up just so you have them in case in the unfortunate event you need them.
But, honestly this should be true of ANY service you use online and care about your data from. It's just that things have been stable enough in the past 15 years that we've all tended to get a bit lazy about it.
Personally, I also have found it to be beneficial to have accounts on multiple instances in the event one goes down, even just for temporary maintenance.
Things do happen, as sysadmins are very much human.
Hope that helps answer your question!