How is it a lead balloon? Go got super popular in the period before /vendor and Dep (later modules). Yes, people wanted and got versions too, but the URL part stayed. ISTM, they had a Pareto optimal 20% piece of the puzzle solved and bought them selves time to solve the other 80% years later.

Go still identifies packages by URL. The recent modules feature just added the equivalent of lockfiles like npm, yarn, cargo, etc. It also added some unrelated goodies like being able to work outside of $GOPATH.