In Respond what does the message "Broad Rule Created" mean?

The event SaaS Alerts Respond - Broad Rule Created is triggered when an event based rule is configured which triggers for 500+ accounts as soon as the rule is saved. 

When the event is triggered, Respond will mark the rule as a Draft, preventing Respond from triggering on that many accounts as this will also flood the partner with emails/PSA tickets.

Looking at the rule logic in Respond, you can search for the occurrences of these events in Analysis to see why the rule would trigger for so many accounts.  Creating more than one rule, only using specific orgs instead of all orgs/all accounts for one rule, can be helpful.