Ignoring whether this is a good business, I feel like this is a pretty terrible way to judge a book. If it took off it would result in everyone just starting their book with a real hook, which only works for a small number of genres and only if nothing else needs to be setup before "hooking" (simple "nothing is unfamiliar" stories).

I've read plenty of books on recommendation that I think are great, but they were not the kind of books that could start with a hook I think.

But, the counterargument to this is if it helps people start books, then who cares if it is an effective strategy or not.