Are there any consumer-centric arguments against this being the default, or is this generally considered to be good for users?
I've heard the argument against setting the DNT field by default (https://en.wikipedia.org/wiki/Do_Not_Track#Internet_Explorer...) so I'm wondering if there are any similar arguments in this case. Presumably Tracking Protection doesn't rely on the honor system, but might being a default spurn the development of countermeasures to circumvent it?
There are websites that break or don't work as expected with an AdBlock plugin. We had to redesign the section of our site that talked about advertising because various AdBlock plugins blocked chunks of the page or disabled the javascript for the contact form. This was very confusing to users even though they presumably made a choice to install an ad blocking plugin.
The specifics of how Firefox has implemented this feature are fairly conservative so that's less likely, but I think you need to be really careful about blocking certain lists of domains by default.
I've heard the argument against setting the DNT field by default (https://en.wikipedia.org/wiki/Do_Not_Track#Internet_Explorer...) so I'm wondering if there are any similar arguments in this case. Presumably Tracking Protection doesn't rely on the honor system, but might being a default spurn the development of countermeasures to circumvent it?