When I played CS:Source in a clan, we had Teamspeak that we rented a server for. When I played WoW and Guild Wars with a small group of friends, we used Skype because it was free. Early-to-mid 2000s.
Lately Skype became too buggy to use as IM, but sound is still solid.
That's more than enough reason to never touch the flaming pile of shit that Skype is today, thanks to corporate development strategies and bloat.
How about "Not being too buggy to use as IM"?