Okay, look, I'm being mildly facetious here, but the genuine, serious point is that the differences interoperability introduces aren't that big of a deal in common use, they're not a selling point to average users and there are plenty of readily available resources to catch up after the fact.

The selling points should be about the features and content. You seriously don't need a tutorial on interoperability before making an account, just perhaps a suggestion of a good default instance to join on the service of your choice.