> how can you ignore all of these bounces from a provider thats likeliest to be the major one you are sending to?

This is the major issue that most of the discussion is missing. It doesn't matter how you want to interpret the word SHOULD, if you want to send to google workspace, you MUST include a message-id. It's not like this is some fly-by-night server with 12 clients.

If you absolutely and completely don't want to include the message-id, then you need to have a warning that your service can't be used by Google Workspace customers. This used to be common practice, blocking communication to servers that behaved badly, and I sort of wish we'd bring it back.