Back in the day, it was normal for everyone to have some sort of multi-protocol chat client like Trillian or Adium or Pidgin, and everyone had multiple accounts too, MSN, ICQ, AIM etc some people even had Yahoo. You wouldn't care which one one of your contacts was online with, you could just chat. The "stickiness" of an individual chat system was very, very low, and the network effects didn't work like any of those companies expected them to.

You see it today with drivers having both Uber and Lyft apps open.