Honestly I think the article is a bit ahistorical on this one. ‘go get’ pulls the source code into a local cache so it can build it, not just to fetch the go.mod file. If they were having slow CI builds because they didn’t or couldn’t maintain a filesystem cache, that’s annoying, but not really a fault in the design. Anyway, Go improved the design and added an easy way to do faster, local proxies. Not sure what the critique is here. The Go community hit a pain point and the Go team created an elegant solution for it.