These are the things people use around here to organise events. Four of those require a persistent account and an app, three of those are Meta for which I'm the loner yelling that I won't touch them with a 10 yard pole and a hazmat suit.
What are you proposing instead? That these should all be decentralised/federated? SMS/RCS? Matrix? email? ICS?
Ideally, yes, distributed. But otherwise almost every calendar service allows events with invited people. Even if each of those services is closed itself, they're all expected to work with any email client and browser. And then you... email messages.
The difference is that all of them work cross devices. That's why I only get video calls with WhatsApp and I never get one using one of the many video call apps of Google. I learned today, by reading this thread, that somebody could have sent me a link to a Facetime call. I never got one. Everybody in my country use WhatsApp for video calls (maybe somebody is videocalling with Facebook Messenger or Facetime, very few with Telegram) and nobody has to worry about which mobile OS the other person have. WhatsApp has commoditized both iPhones and Androids here. When people choose to buy a phone they don't think about how they'll make calls or send messages. They install WhatsApp, because they have to or they won't call and message a lot of people, and the problem is solved.
Edit: by the way, probably every single phone has builtin interoperable 1 to 1 video calls from the days of 3G. I remember testing them in late 2002 / early 2003. They worked and probably still work unless they retired the standard because everybody is using apps.
You (like quite a few others) didn't read the linked press release which would have been a good prerequisite for joining this conversation. I guess you really just wanted to unload on your least favorite tech company.
I did read the press release, and this seems pretty open.
"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."
So what's objectionable about this?
Your buddy can invite you to a party using this thing and you can RSVP without installing an app or creating an account. That sounds pretty good to me. You have a web browser, right?
ICS, yes. Like most event services that aren't Meta work with.
ICS + e-mail is the established standard. It works, and has worked for decades, to the point people don't think about it in terms other than just "calendar invites".
What are you proposing instead? That these should all be decentralised/federated? SMS/RCS? Matrix? email? ICS?