> Guests can view and respond to an invitation using the new iPhone app or on the web without needing an iCloud+ subscription or an Apple Account.
Video calling is orders of magnitude more complicated.
They're not really comparable.
It's service slop after all.
Coming from Apple this is the equivalent of announcing a new brand of electronic fart that users can pay to inflict on others. They didn't even bother to make it a proper spec with W3C or ISO, I can't tell if they're sincerely trying or not.