Correct me if I'm wrong, but can't I open Gmail, send someone a message (@letshum.com or @facebook.com), and they receive it as a Hum or Facebook chat message? Then, they can reply to the message in their chat client as if it were a text, and it goes to my Gmail? That seems quite similar, and in both cases I can communicate using email, while my friend uses chat. This seems to be the underlying reason why both services give every user an email address, so I fail to see how this sets Hum apart from other chat apps.
Facebook has announced their intention to retire @facebook.com addresses, forwarding mail sent to them to the user's primary email address and making all chats involving @facebook.com addresses read only.
If I may, linkedin does allow users to correspond with each other using both mail clients or directly through their platforms. The part that I am not too sure about is how does Hum solve user problems that whatsapp/wechat can't. The gap I find as a user is that unless there are ways for Hum to integrate with the fragmented contact databases we have across the various social networks (i.e. my gmail, 1k+ linkedin contacts, facebook friends, twitter correspondence etc) and make my life easier, I may not venture and try yet another chat platform.
Which chat program do you know can send a message as an email? And receive chat messages via an email address?
It seems the idea behind this, is that it's a "persistent chat".