GitHub is a hugely successful company. They make a shit load of money. Your idea of success is not in congruence with actual success.
Everyone is different, but I think most people would not picture a source control product where search, issues, and on-prem are each so terrible, the default solution for that feature is to use a completely different product from a totally different company, which solves that specific issue (Sourcegraph, Linear, GitLab, respectively).