Result #5 on a query that generic is quite far down when you consider that all of the top 4 results would equally answer the question. So many people might not get as far as gobyexample.com using your search term example.

Plus on queries that generic, a lot of people might just go straight to golang.org and re-read their docs.

Obviously this isn't the case for everyone, but it would explain why I've personally never heard of gobyexample.com before.