[jakejake]

This doesn't strike me as a developer tool (though it could obviously be used by developers). It's for consumers. I don't know of many consumers who want to receive notifications via webhook.

If they did do webhooks then you could write one that sent out SMSs though - leave them to do the hard part while cutting them out of the loop!

Also I think it's push notifications, not SMS.

[hackercomplex]

This kind of thinking reminds me of Twitter in the early days where one founder was trying to pigeonhole it into being for a particular use case. Twitter began it's life as an SMS play also if my memory serves me correctly.

Really it's up to the startup.. do they want to try to eventually become the Internet's primary notification propagation channel or are the only interested in catering to a particular mobile phone use case ?