All good points except for the first sentence. :) The thing is, if you're building a startup, you want to deliver value to your customers as quickly as possibl

All good points except for the first sentence. :) The thing is, if you're building a startup, you want to deliver value to your customers as quickly as possible ... you know, so you don't die. Customers don't care whether you used an API or rolled the functionality yourself. For an early stage startup, implementing or troubleshooting back-end functionality you could have outsourced to an API is, to a first approximation, a waste of time.