Because although it sometimes takes just short of a century, the guy usually comes through. I've bought from him multiple times, and he's always delivered and at some pretty good prices.
Perhaps, but there are many, many other dealers out there who always deliver and price their goods competitively, and are a tad quicker, too.
Speed of delivery is as important as any other facet of the transaction - apart from solid packing, maybe the most important. I believe that Alex H's complaint wasn't that he wasn't going to receive the books, but that he wanted them before one of Joe Kubert's very rare signings, and he didn't get them in time.
Us fanboys are a nervous lot as you know Vince, and after several months of non-delivery the anxiety that one is not going to receive the books one has paid for becomes too large to ignore.