They don't have to favour anyone, they could release DLC for both platforms simultaneously. But they won't.
Yes, it's called marketing. Clearly, you, and most of the other teenagers on this forum, have no idea how businesses work. Not an insult, just a fact.
You want to complain and whine about things, yet you have absolutely no idea why decisions are made as a fan. You aren't in the chairs of the devs, Todd Howard, or Pete Hines. You don't have multi billion dollar corproations breathing down your back, making you multi million dollar offers, to push their version of the product you are making.
If I'm wrong, and you
do deal with those situations on a daily basis, by all means, correct me. But, well, 99% of the people on these forums
don't know how that is.