The value of YC also depends largely on what kind of company you want to start. If you're looking to start a small shop making $500k-$2M (max) a year in revenue with 2-3 people than YC probably isn't for you because that type of business is not venture fundable and thus the venture connections that YC can get you aren't really worth much. However, if you're looking at something that has the potential to be VC backed scale ($10M/yr+ at some point in the future) then the introductions and connections are necessary and the value of YC is clear.
Also, I would add that I think the YC alumni network has become one of the most valuable parts of YC. There are enough alums now that basically someone has had experience with what you are going through and can offer good advice, imho that is the hardest thing about YC to duplicate.