The point of outbreeding is to breed for certain traits, then breed them back and stabilize. And repeat. It helps to have a large number of individual plants to choose from when doing this- the more, the merrier, really. Doing it well takes a LOT of space!
My hat's off to guys who do it the hard way like this, I don't have the patience for it.
I have a different take on strains and all the crossbreeding going on right now. I see an explosion of variety, not a solution, and an eventual profusion of varieties for growers and tokers to enjoy! And, the dark side of pot biotech gone mad, Monsanto style.
While it is true that many land races are being contaminated, this is exactly the process by which evolution happens. We've just accelerated the process many times over, and I find that exciting!