i don't think it benefits authors. I think searching for a book and reading a few pages and being done with it. That isn't ideal for authors at all. Some people just need to read a few things in the book.

Oh, man, I hope you don't find out about this terrible place called a library where people do that kind of stuff all the time.

Or the bookstore.

but libraries pay for their books. And a library might buy many copies of a popular book.

And they lend them out. Which is considered fair use.

Just like full-text search, now.

As was said by a sibling comment to yours, people do this all the time in bookstores too.

Corollary: Google shows a snippet of text from a website under their link. If what I wanted to find out is contained in that snippet, I won't necessarily click the link. Same thing, but instead of a pointer to a website (which, in this example, just lost a pageview), it's a pointer to an book that you can purchase.

More funnels to conversion mean more books purchased.

you can loan a book out to one person at a time. i think it's a little different.

not every author wants to increase sales. I would rather opt out even if that led to a decrease in sales. I can't make someone else increase sales by making them use my new sales platform for free.