So let's say as part of my signing up through a client, I get asked which topics/communities I'm into, and I choose Science, Politics and Cooking.

Not sure how the client would handle any duplicates there, but I digress.

Now let's assume I piss off the management of the Science relay and get banned.

I no longer have a way of reaching the users of that Science community, even though they may be subscribed to me, since we no longer have a relay in common. If I create a new Science community, how would they know about it? How would the client decide to recommend it to anyone? Do I need to host a relay to do it?

Worse yet, maybe the Science community relay just disappears one day. The entire community erased.