Interesting idea, but it seems likely that the data this collects may not be very useful as a way to estimate the effectiveness of landing pages.

If I don't belong to one of the markets that the landing page is trying to sell products or services to, I shouldn't be able to vote -- if I vote, I'm just polluting the dataset of what their actual potential customers think of it.

If the two landing pages being compared aren't targeting the same market of potential customers [+], it's unclear what comparing them achieves.

It's unclear if voting on a landing page in this kind of artificial setting is predictive of something more material like how often a potential customer proceeds to sign up for a demo, or pay for something, or call sales.

[+] or given a lot of these are AI landing pages, I guess they're targeting investors.