I think that kind of loss of meaningful interaction is a pretty small thing, but it can add up over time and have a greater impact with high usage of services like Google that automate things that previously generally involved more human interaction. And sure, no one's forcing anyone to use Google or Amazon instead of talking to people, but it's a fairly subtle opportunity cost that comes with using those services. And those kinds of services are convenient and useful enough that it's quite easy to make a habit of using them, and habits aren't easy to change.
I think many easily turned to the web for recommendations because as wholesome these kind & knowledgeable book and movie human recommenders are, they simply weren't available to a lot of us.
Amazon book recommendations and keyword search are garbage. Sometimes even a direct search for title and author name will put the result halfway down the list. The two good things Amazon has going for it are the huge catalog (great for finding the right ISBN), and reviews dating back to the 1990s. Makes it easier to decide whether or not to purchase the book from a more ethical retailer.
Out of all the online bookstores, Thriftbooks has the best recommendations in my experience.
The best ways to find good books are still bibliographies and large public and university libraries - browse the shelves, ask the librarians. Online library catalogues usually beat online retailer catalogs for keyword searches.