I agree, I thinkg though people use it because of next day delivery, they get used to it and it becomes automatic to order from them.It does appear their prices tend to be more expensive than ebay for little random bits, tech can be cheaper but not always, and other stuff varies. But there's a lot of poop on there backed by questionable reviews.
Similar to how everyone says I need a hoover rather than vacuum cleaner - its become synonymous with shopping, and that's what they rely on.