It is well-known as a result of the expert reports in US v Google that generally software users do not change defaults
Whereas providing an option or a setting that the user must locate and change doesn't really mean much. Few users will ever see it let alone decide to change it
For example, why pay 22 billion to be "the default" if users can just change the default setting
Mozilla is certainly paddling upstream. Of all of the AI-integrated apps and sites that I'm subjected to, I can think of exactly two where it wasn't obnoxious and a pain in the neck to disable.
Kagi. Zed. That's it, that's the list.