My 2 cents on this is that I while agree for immutability in the context of public/social messages, I also feel it would be a drawback for private messaging. 

Nowadays even Whatsapp managed to have editable messages. 

 As I say in my article I don't think it is a problem to have edits in private messages and most other kinds. It's mostly kind:1 that must be protected at all costs. 

 right. I did read it, then I forgot it. 
Cool.