How does this set it aside from Amazon, aside from "generally a good product"? Massdrop marketing seems to be all about the pricing when in reality its just a curated list of (ostensibly) good products.

Massdrop's keyboard section typically sets it apart from Amazon. Not sure about other categories on the website.

Mass drop sells DIY kits to build ergodox keyboards which you typically can't buy anywhere else. Additionally they just arranged a production (with a lot of help from a Redditor) of custom key caps (Triumph GMK Adler https://www.massdrop.com/buy/triumph-adler-gmk-keyset).

Edit: just remembered I looked at buying headphones from Massdrop once. The starting price for the group buy was MSRP and the final unlocked price was the same as on Amazon. This definitely mirrors what others are saying.

In my experience I have also had mixed results buying non-keyboard related items on massdrop, but the keyboard things I've bought where excellent and at great prices.

Well for one thing there's often stuff on Massdrop that you can't get from Amazon. If the item is on Amazon it's generally about the same price, but I've definitely picked up things from Massrdrop that aren't on Amazon for a much better price than I found anywhere else. But yeah, I see it as a curated list of good products with the occasional deal.