It's not that they didn't warn bluesky specifically. It's that they didn't warn relay operators in general. And IIRC they just needed to coordinate with a single relay operator who is reasonably trusted (ex blacksky or eurosky) but they didn't do that either.

The default rate limits are quite reasonable but big launches will blow past them so you gotta coordinate with someone.

And note that the relay federation/gossip agreements are largely manual configuration at the moment. Until someone pushes a proposal for an automated/dynamic topology management algorithm that doesn't get plagued with spam issues it'll stay this way.