ICQ was nice. It had an IM, a user directory, and alternative clients without games etc, until its owners went crazy.
Old Skype was nice. It had fast file transfers, a good Linux client, network efficiency etc, until Microsoft.
I think everybody thought that just like from proprietary ICQ everybody went to proprietary Skype and it was nice, there’s going to be an equally good alternative when Skype rots and people will move to it.