Maybe, but delivering exceptional value in one area (books), is probably correlated to providing value in other areas (AWS, retail, etc). You could imagine a s

Maybe, but delivering exceptional value in one area (books), is probably correlated to providing value in other areas (AWS, retail, etc). You could imagine a similar situation with Google. You buy google stock because they created a really good search engine. But being able to deliver a great search engine also, it seems, is correlated to providing great advertising services, cloud computing, and email. Being good at one thing is probably correlated to being good at other things (especially if they are related). While being bad at one thing is probably correlated with being bad at other things.