I’m pretty sure it used to be easier to get people to move to new things like new forums, Xfire, Ventrillo

In some respects it was somewhat easier to get them to be on multiple platforms instead of moving. Think of the original messenger proliferation, where sometimes people would be on IRC, XMPP, AIM, ICQ, MSN Messenger, or etc. so much so that you had software like Pidgin and Trillian to help consolidate server/chat rooms and friends lists to more easily chat with all your contacts.

Even with Ventrilo, I remember being open to also switching to Mumble or vice versa if there was some hiccup with either.