The real hole is "instant messaging". Somehow every few years we got from ICQ to AIM to Paltalk to Skype to Facebook Messenger to Slack to ... (at least Altassian had the decency to take HipChat behind the woodshed and shoot it)
The strange thing is that these services dry up, blow away, get replaced, but they don't seem to improve on what came before.
There is a standard, XMPP, but the only people who care about it are firefighters, cops, and soldiers. For all the anger at internet giants these days, I can't see for the life of me why people aren't pushing for open instant messenging.