This isn't Google... the search button can be really unhelpful. Sometimes people create a thread about, say, FRED, and people complain that they haven't used the search button. Then I do a search on what the possible key words would be like 'FRED nebulae' and the thread on the top 5 of the list will be the original one.

In this thread's case, that's not the..er...case. There IS a relevant thread, but it has several pages and vBulletin forces you to sift through it all, which takes a long time and if you're not in the mood for reading, creating a new thread is more convenient and faster. So don't blame him...he's just following human instinct.
EDIT: Proof that it is faster is provided by the guy below me, who replied like 2 minutes after my post.