I've never been part of web development, so I've only seen one half of the equation. AAA game development includes dedicated teams of QA testers playing throug

I've never been part of web development, so I've only seen one half of the equation. AAA game development includes dedicated teams of QA testers playing through the game each day, flagging all bugs they come across and verifying every bug which is claimed to be fixed. That's the best source of stability in my experience. At the biggest studio I've been part of (three offices, with about a hundred people in the main one) we also had a number of automated tests (AI running through certain missions and doing events together) where failures would alert those with contributing commits.