Some people are just... *sigh*.
Yeah, well... y'know... that's just, like... your opinion, https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQPvuzuThHBZU-mS4fwHaKaoV1f-gsNfn4oSR9rzc3A10NLbkVvOQ.
Maybe you guys are looking in the wrong places, i have had no problem finding goat horns, straw, and glass. All i can say is look harder.
Considering that Skyrim (and all TES games back to Morrowind, for that matter) has a pretty good track record of giving players bug experiences that are not common to all the copies of the game, as well as some cases that are apparently unique, it is understandable that some people may have a problem that others do not.
That said, instead of talking down to people you should perhaps consider yourself lucky that you are not experiencing the same problem.
On a more thread-related note, I've yet to run into any restocking issues but am disconcerted with the number of goats horns typically available with vendors. Is five the standard amount? Is that enough, restocking issues notwithstanding?