Games have gotten more complex and so have the teams to make them.

It use to be a few developers juggling multiple rolls to entire departments that only specialise in one thing.

To get all those different professions together to build a game is really hard because of communication. The best people are the ones who can do a bit of everything but large companies don't want that, they want specialists who do one thing.

You can program? You can also create 3D assets? Your good at audio? Well tough you have to pick one and you'll probably never interact outside your team.

And this leads to lots of fantastic ideas and creativity being lost not to mention bugs and other issues popping up.