The most important reason for outsourced testing is that most developers release their in house army of manual testers after a release. Most studios don't instantly have another game ready for testing after the current one releases. It takes time for the developers to get the next game in a state where testing is even relevant. So this necessitates getting rid of many of the testers in-house after a release. That is why most testers are contracted rather than salaried. This is 98% of the reason that outsourced testing exists.,(reply>), And it's also the reason why most testers at any given time are juniors. QA is vital to the development process and yet gets the smallest investment possible in every single situation. It's the first place that's culled when management wants to save money, and it's the place that puts in the least amount of effort into talent retention.