Indeed, but there are a lot of situations where a focused specialized widget made by a small team will be better than a general "best widget" made by a large te

Indeed, but there are a lot of situations where a focused specialized widget made by a small team will be better than a general "best widget" made by a large team. The further you stray from the use cases of the "best widget" the worse it gets. Writing another HTTP server does seem like an inefficient expenditure of time, but we wouldn't have Nginx or smaller tools like Mongrel if the existing "best tools" were good enough. Game engines benefit you even more to be custom because the further your game strays from another Unity game, the further it stands out from the crowd of 100,000 smartphone games.