With imessage pirating OSX will let you connect again (although it's a major pain, and you have to go generating serial numbers and trying to log in.) Is there something like that for Android? Or do you just not get to talk to your friends if you take the sim card out of your old phone.
imo the best reason to abandon every chat service that does not have an opensource client.
I use iMessage for what it works well — short temporary conversations. But if one wants to maintain a community there are far better options. Like Rocket Chat, Slack or Discord.
So when you switch OSes you get kicked out of the group.
For some reason there are a number of people on hackernews that are really struggling with this idea and I'm kind of surprised it's so difficult to understand. I thought the last guy I talked to was just particularly dense but maybe I'm failing to communicate it effectively? Maybe it's harder to understand than I thought it was? I'm not sure.
So I guess my experience is that you don't get kicked out of the group.
what you have probably mistaken for is send to multiple destinations and reply-all.