Yes, they're really friends. If my friends all use whatsapp to organize parties, and I refuse to use it and force them to email me as a special one-off, am I really a friend? Because I know they'd love to have a back-and-forth conversation about timing/place/duties related to the party, then have to constantly send one-off emails to get my feedback.

Let me guess - in your world they're all assholes for not constantly inconveniencing themselves to cater specifically to what you want. Or you just literally have no social life, because picking up a phone isn't really a viable option to plan a party with a large group of friends. And while email will work, when nobody else wants to use it and you try to force the issue, you're an asshole.