Proof? For what? It's common knowledge that Bungie has around 500 developers working on Destiny. As for that every game does this, It's obvious, do you really think it takes 3 months to create an entire dlc? If you do then your crazy, the art alone for Crota would have took months to draw by hand, make it into a computer graphic, animate it and add it to the game, making it work for everything else, that's just one character imagine how long it takes to do this for the entire raid. As for that dlc was included to reduce download times, here's a link: http://www.gamespot.com/articles/bungie-explains-why-some-destiny-dlc-is-already-on/1100-6423327/