That still ignores the existence of a huge usability problem. The investment of time may pay off in the long run, but IRC is large enough investment (and ongoing maintenance, ZNC doesn't just take care of its self forever) that people will take a route of less resistance when presented.

This all reminds of a few years ago when folks were banging on about how we needed to use Gitorious instead of GitHub for Open Source hosting. Gitorious is dead now and it wasn't until GitLab came along and recognized the usability problem that we got a viable Open Source alternative.