Not sure about the down mod, but I think the point of the OP is to address projects that have the goal of driving a "startup" business.

In addition, with mobile, getting rid of any network latency you can is going to help.

In general, though, I think you are right to ask the fundamental question. That said, it's something a lot of people end up needing anyway and it helps if you design for it up front.

tl;dr - If you're building a low-volume site, the OP probably doesn't apply to you.