Google Wave primarily failed because:

1. Performance was never more than tolerable

2. Invite only access

3. Invites didn't go out immediately, just added people to a pool of potential future invites

A product that required the network effect of a large connected userbase to succeed only had random individuals with access. Literally no one I invited and would have used it with got in, and I was in one of the first couple batches of public users to get access. A spectacular self-own on Google's part with that rollout.

I never understood the real use case of Google wave.it had lots of features without a clear goal. Google docs seemed enough for all those but the curious.