"Decent clients" won't expect users to become relay experts.
While some are begging people to use 2-3 relays, others are saying "every group of friends should have their own relay", and "topic-based groups should be organized by relays". So, you're advocating that Nostr shouldn't have groups, and everything should be 100% public? Or am I missing the magic sauce that allows for privacy with a 3-relay-only setup?
At one point, I had about 50 relays, and there were no diminishing returns or degredation of performance.
In addition, you can't guarantee that the people following you are going to only use "decent clients" that will "find your event anyway".
If having more than three relays is a problem, don't let your users do it. If adding specialized relays to a category they aren't meant for is bad, don't let the users do it. If a client/relay does things your project doesn't like, solve your problem with your code.
Attempting to dictate the behavior of the masses through notes isn't going to work.