There’s no reason you can’t build and launch a product and get hundreds of paying customers by yourself.
Programmers don’t need a co-founder
Justin Jackson

I find it’s not uncommon for technical & non-technical entrepreneurs to seek out one another simply because they’d prefer to focus on what they know and love, rather than a lack of knowledge being the impetus to find a co-founder. Also, as the saying goes, “If you want to go fast, go alone. If you want to go far, go together.”