Amazon has Reasons not to let that negative review go up

After spending ~5 to ~10 minutes filling it out I get this message.

This item is only eligble for Amazon Verified Purchase Reviews.

What a waste of my time! I bought the thing, Amazon knows this, so what is this about "Amazon Verified Purchase reviews"

Note that I only got this message AFTER trying to leave a 2 star review. What would have happend if I had left a more positive review? Would that be allowed?

My favorite 'dark pattern' at Amazon was how you couldn't navigate away from the checkout page: the Amazon logo was unlinked and the rest of the usual layout was absent. They changed this recently to make the logo clickable, but they still aren't letting you leave that page without a fight, and there's only one place they wan't you to go back to: