Fair point, but isn't the jam example also a product aisle with 24 varieties of jam? My current frontpage recommendations include around 15 laptops and 15 books - I can't possibly buy all of them - aren't they asking me to choose? If they showed me just three from each product category, and fewer categories overall, I might actually be interested in the recommendations.
I guess its something to do with the ability make a decision and short term memory. Interchangable products makes decision making hard because they need to be considered at once. Products in other categories don't need to be held in your head while you choose between them.
well at that point they really have no idea what you need, throwing up the crapload of choice is just there in the hopes that you see a good deal and click buy,
They figure that if you are looking for something specific, you'll just use the search feature