"Total cookie protection" from Firefox

Except, how can they know that you are using this feature? All they can tell, is that their cookies are in the jar where they put them, and that some other site's cookies aren't. Which could just mean that you've recently cleared your cookies, or re-installed your browser, or fired up a new VM.

Of course, they might start trying to prevent use of Firefox altogether. In a previous decade there were sites that attempted to prevent one from using any browser that wasn't Internet Explorer. I just stopped using those sites, although it was also possible to tell Firefox to "lie" and identify itself as IE. Any organisation that sells you stuff is unlikely to want to annoy its potential customers in this way. "The customer is always right".