That is true, but it is very basic and depending on the browser how it is implemented. On traffic heavy sites, which I assume gates blog is, js gives you full control over what get loaded when and at the same time enables tracking how far the user read the article and which parts he most likely skipped.
I am not saying that this is good, however if you have these requirements js is a valid choice.
Basically no one has a requirement to track what someone else is looking at. In fact, if not given explicit consent by the person being tracked (like they've specifically sought you tracking it for them, e.g. marking their place), we should frankly criminalize it. Mass surveillance should result in jail time.
