It's a disservice to tell people their mastodon instance doesn't matter, just sign up anywhere
If your server abruptly shuts because the owner gets bored, dies, runs out of money, that's a problem, no way to transfer. If the owner decides to ban people for something arbitrary they can
For mastodon to take off we need instances that are reliable, stable, resilient, fairly run. Or to not tie online identity to a single instance
P.S. Reliable so far doesn't mean reliable long term