All of the write relays, yes. I am adding more popups to help people setup their relays correctly.
The event is replaceable, though. It shouldn't take extra space in a regular relay that deletes old replaceables as they should. Rate limiting is not a good idea for any replaceable.
Most of the work is on fixing the Outbox relay list other clients have created based on the kind 3 list. The Outbox list should have 3 relays max. Many people have 20 relays over there, which is terrible.