If these companies instead spent their time on improving the UX of their sites so that users (and not some creepy AI Clippy) could easily find stuff they cared about and in the sizes they needed then the companies would easily dominate their respective markets. Taking a cue from the physical world if I walk into my local grocery store I would be seriously creeped out and annoyed if I was greeted with a cart full of recommended items based on my previous purchases.