It does when you're still struggling to understand that putting two buckets of milk next to each other doesn't fully double the quality of the buckets of milk, although it does give you twice the milk to start with. But twice the milk costs twice the COW. And doesn't give you twice the quality of CHEESE on your screen.
As Memo has brought the cow to my attention, it is money. You buy 2 GPUs for the same price for each GPU, but they don't deliver double the performance. However, it gives you more GPUs to have to switch around and store, meaning that two crappy cards that have an added price over a significantly better single GPU config for somewhat less. A single decent GPU will be much more future-proof, as it alone is designed to power through games like a boss, and can be sold for much more later than you can sell two piece of crap cards separately.