When it comes to shitty interoperability, Google takes the cake.
No one ever claimed FaceTime works on your android. They wanted to open source it and got fucked on patents.
Try using gmail to send a regular iCalendar format invite to an event. If they just happen to have used that email for a google account, fuck you it ends up in the Google calendar account they likely didn't know they even had, and never goes to their email.
THAT is unexpected, and arguably deceptive behaviour.