It's poking fun at the Epic Games Store, which launched as the most barebones piece of shit imaginable and didn't get basic features all online stores have had since the nineties until years after launch. The lack of a shopping cart was the most famous, and I'm half-convinced they only added one because people were getting locked out of their bank accounts (since you had to buy each item separately, the many transactions close together tripped some banks' anti-fraud heuristics).

They didn't learn anything from it either. Their mobile store launched years ago (and years after the PC one) and still doesn't even have a library. There's just the main store page listing every app they sell, and any you own will have the price replaced with a download icon. No sorting or filtering either, of course.