Earlier quoted context omitted.
The post does not suggest avoiding designers completely. It is about timing. Of course this depends on the type of startup, but in many cases you can absolutely ignore brand message until you have some level of basic functionality and alpha testing done.
I put more faith in alpha testing based on a design without a single line of code written, than on code without a single thought put into the design.
A developer might not do as good a job at it as someone who focused their career at it, but I would be surprised if developers couldn't put together something that was at least passable if they put a modicum of effort into it.