I'm not sure, but from what I understand, they are unlinked because they charge so much for their drugs. Now, I'm not a pharmacist, but I'm pretty sure that whenever a new drug comes out, it has to go through all kinds of testing and crazy expensive processes. That's why new drugs usually cost a lot. But then, once it is approved and they have been able to pay off all the testing fees, they will rarely ever drop the price of the drug.
Personally, I don't have a huge problem with them, but maybe that's why some people might say bad things about them.
I wish I was more informed to tell you, but I really don't know much more than that.