1) They used other services (e.g. Evite) which had the same effect
2) Nobody uses those other services anymore (okay, I got one evite from the one friend who refused to use facebook...and then somebody created the event page on facebook and all the party planning promptly got hijacked and moved there)
So your choices are to use Facebook and get invited to parties, or be like that guy from ten years ago who refused to get an email address and was butthurt that nobody would pick up the phone to personally invite him to the party.
Whenever something is up, everyone knows I won't get the memo, and they give me a mail/text/call. Usually more than one person.
And you can't compare that to email vs phone. Phone is costly, time consuming, single threaded. Sending a message on Facebook or an email doesn't make any difference.
What about relationships with people?
What about carrier pigeons?
What about personal servants?
All of those things are able to do what you're complaining about, they just take slightly more effort.
I guess it's to each his own - is your support of a terrible, invasive company more important than your convenience? That's up to you.
And it's not about my convenience, it's about not inconveniencing my friends by demanding that they remember that I'm a special snowflake who won't use the dominant communication platform of the day, and I must have my special needs attended to by using older, more inconvenient channels each time they want to send out a mass party invite.
The fact that computers are too inconvenient to use for communication without using locked centralized platforms and proprietary software is a testament to the failure of computers as a communication tool, rather than a good argument for the necessity of Facebook, which actually is terrible and worth resisting.
Or maybe social communication platforms are a natural monopoly and the computers are working just fine.