This is because at that point, our focus turned to licensing our (patented) technology to businesses. We still have B2C customers who use the tools that he originally built (and which have been updated by contractors after he left), but now the vast majority of our revenue comes from our B2B licensing.
We are pretty unique in this regard, since most startups aren't able to generate much revenue from licensing in this way. Specifically, when we work with our licensees, we provide a JS library that they plug into their own platform. We don't need engineers to do integration work, or provide support.
My technical cofounder provided a lot of value in getting us to where we are, for sure. But needing a technical cofounder to launch doesn't necessarily mean you need one all the way along.