I don't think it's at all surprising that there is no relation between tech stack and business success. End-users don't care if you use a single PHP file or a Go binary, they never get to see that anyway. So I don't really see "it was all a single PHP file" as a gotcha. The whole thing could've been coded in Assembly, the difference is in the effort required for development, ease of maintenance/scaling up and how wel…
Also, this is not really a "tech" story. Everybody is building websites these days. What counts is what business you build with them.
Yes, the business you're in matters. No, it doesn't matter how you build them - as long as it's quickly. If you outgrow you're overly simplistic stack, that is a _great_ problem to have.