>>s1k3s+Z5
There are also ways to track you on the front end without JS but I think "This website will not… track you" is just a promise from the not something that followed from the lack of JS anyways.
>>zamada+M7
It could also be a canary in case the site gets bought out, and the new owner wants to implement invasive tracking. If a site has "will not track you" when you visit it, but the next visit it is removed...