[nl]

The missing piece, though, is the revenue model - the users who would generate more than 30 million messages in a month are the same users who actually might have their own back end, and the wherewithal to use it

This is true, but if you had a service with the potential to generate say 50 million messages per month would you spend $60/month and use this, or multiple thousand dollars to develop your own?

(Also, note that a big market for this is mobile, not just javascript on websites)

[kozubik]

Ok, fair enough. I'm still wrapping my head around JSAI (javascript as infrastructure) so bear with me ...