Ok let me reword it differently: the 500,000th most popular site on these lists most likely isnt the 500,000th most visited and it might not even be in the top 5 million. These data sources are so bad at capturing popularity after 50k sites or so simply because they dont have enough data
I haven't tested this, but the "Cisco Umbrella 1 Million" is generated daily from DNS request made to the Cisco Umbrella DNS service. That seems to be a very good and recent dataset.
It does count more than just visiting websites though. If all Windows computers query the IP of microsoft.com once a day that'll move them up quite a bit. And things in their top 10 like googleapis.com and doubleclick.net are obviously not visited directly.
So while it is quite a reliable and recent dataset, it is not a good test of popularity.
