Doesn't look like the information on that site is correct. Or at least, it disagrees with https://www.henleyglobal.com/international-visa-restrictions...
The differences are quite striking, the US isn't even in the top 10.
It lists the US as a number 1 country there (with 174 visa free countries), I guess they omit it on the free list to gather email addresses.
I think your link takes a very narrow definition into its rankings. I'm not sure how broad the index in the story is, but it seems to take into account more than just visa requirements.