Read first pages of novels, and reveal the author and title if you're hooked

I think opening "prologue" scenes like this are mostly about priming the audience's expectations. Movies do this too; the story of The Matrix begins with Neo working as a corporate drone, but the opening scene is an action sequence with Trinity getting chased by a police as a promise of things to come. There's value in letting the audience know what kind of story they're in for, especially if you're planning on taking awhile to get there.

Notably, these kinds of scenes aren't there to sell the audience a false bill of goods. Quite the opposite, in fact: the first few chapters of a story aren't always representative of the whole, hence the addition of a prologue to give the audience a sense of what's to come in later chapters.

As an example of what can happen when an author doesn't do this, Dan Wells' I Am Not A Serial Killer is about a teenager who works in a mortuary and investigates a series of brutal deaths around his town, and discovers that the killer is actually a millennia-old monster. The supernatural reveal doesn't happen until halfway through the book, and if you go on Amazon and sort by 1-star reviews, you'll find a lot of them come from people who thought they were reading a crime story and then got upset when they discovered they were reading a paranormal YA novel. When it came time to publish Wells' next book, his publisher told him, "This time, we're putting the monster on the cover of the book."

There are a number of sites where people post serial fiction as it's written, chapter by chapter, and many popular web serials began with opening chapters of around 500-2000 words (2-8 pages). These sites usually offer writers validation in the form of likes or star ratings, a view counter, and comments from readers (who will often respond with short affirming messages like "looking forward to chapter 2" or speculation about where the story might be headed).

Royal Road is one of the newer and faster-growing sites, notable for being the biggest home of free LitRPG stories. Archive of Our Own (AO3) is a site mainly for fan works, though there are a number of people posting original fiction there. AO3 is currently a closed site with a queue to get in (most stories can be read by anyone, but an account is required to post), there's usually a waiting period of around 10 days after you submit your email address to the waiting list.

There are also some forum-style sites like Sufficient Velocity (and its progenitor Spacebattles), where the forum software allows authors to "threadmark" certain posts in a thread and label them as chapters to separate them from the posts that are discussions/comments. Readers can choose between "Reader mode" (which just displays the posts that have been labeled as chapters by the original poster) or a regular forum mode (where they can see all of the comments from other posters between chapters). Although this forum-based approach might make it feel like it's less optimized for sharing stories (as opposed to sites that are tailored specifically to that purpose), I've found that the forum setting makes people much more likely to comment on stories. While these forum-based websites might not have the biggest audiences, they certainly seem to have the most engaged audiences, which I think makes them more valuable if you're looking to validate a story idea.

You are judging the book on the basis of a page here. Not much different from judging the book on basis of the cover.

Editors are known to only read the first few pages to make a decision on whether they even want to spend any time on a manuscript. The first pages of the book who survived going through an editor are designed to achieve that already.

This is actually how I select books in a book shop. I admit I was ruined by all things tech with very limited attention span. In fact I only read the first paragraph over about a dozen books on the website and finally decided on one which turned out to be The hitchhacker's guide to the galaxy.

My suggestion here is not necessarily putting out the first page but a page the author feels most representative of the story/view/idea. Personally I would either draw to a unique plot or some really smooth/beautiful verse. In both scenarios, I don't think the first page may necessarily be representative enough, leaving me the shame of missing a damn good book.

Love the idea though! Thank you.