"I was the tech lead responsible for scalability/reliability at IMVU for a long time, but eventually our bottleneck clearly shifted from reliability back to marketing/product development. "

I read it as, "Once we got reliability sorted out, the bottleneck moved to marketing/product development."

He never said IMVU could have been built without good programmers(of which class, he is an instance), but product dev/marketing became (or were) equally important (or more important) and so he moved to that team. At least that's how I read it