I have the same reaction you (and Garry Tan) do. Having a members-only upscale e-commerce wasn't invented by Fab, Gilt Groupe was doing it four years before Fab was founded. There aren't that many variations on what a members-only-bouncer page can look like.
Aside from the choice of layout of the product page, which itself is generic, I don't see anything in common. Having the time remaining in the header bar has been commonplace on flash sale sites (Groupon and clones) since before Fab was ever founded.
E-commerce layouts have been studied in depth, it wouldn't surprise me if the layout choices (like repeating the add to cart button at the top and bottom) by Fab were not arbitrary but based on known best-practices.
Aside from the choice of layout of the product page, which itself is generic, I don't see anything in common. Having the time remaining in the header bar has been commonplace on flash sale sites (Groupon and clones) since before Fab was ever founded.
E-commerce layouts have been studied in depth, it wouldn't surprise me if the layout choices (like repeating the add to cart button at the top and bottom) by Fab were not arbitrary but based on known best-practices.