Easily defeated argument. If that website doesn't want members of the public accessing it (and picking and choosing what parts to access), then don't make it publicly accessible.
You're assuming they don't want the general public accessing the website, perhaps they do and would also like the revenue that comes with the ad's served on the site, because that is, broadly speaking, how the ad funded model works.
I personally think ads are a terrible model but a paywall is an entirely different business model with different considerations.
This includes links to tracker filled javascripts and images hosted on ad servers.
Rather than gimping the browser stack for everyone, websites should use the tech they already have. Like rendering ads directly into the page contents.