> This is the same as if one set of friends are on WhatsApp and another set are on telegram etc… and having to deal with either switching between apps or dealing with reduced capabilities.

It's not really the same, since if a group is using WhatsApp and you want to join, but don't have WhatsApp, you can simply install it. The same with all other messaging platforms.

With iMessage you can join over text/MMS, but it will make the experience so much worse for everyone that most people (from my experience) will simply not allow you to join.

There's a reason this is a major cause of dread for socially vulnerable teenagers https://www.wsj.com/articles/why-apples-imessage-is-winning-... but it's not that different for adults.