Sounds like you’ve maybe never actually run a service or API library at scale. There’s so many factors that go into a decision like that at a company that it’s never so simple. Is the person impacted influential? You’ve got a reputation hit if they negatively blog about how you screwed them after something was working for years. Is a customer who’s worth 10% of your annual revenue impacted? Bet your ass your management chain won’t let you do a breaking change / revert any you made by declaring an incident.

Even in OSS land, you risk alienating the community you’ve built if they’re meaningfully impact. You only do this if the impact is minimal or you don’t care about alienating anyone using your software.