Perhaps this is the way to think about it: For some people, in some situations, perfect anonymity is needed, with nothing less.
For other people, or other situations, "nearly" is good enough, based on what you want to accomplish: 1. Preventing ISP's from tracking and selling your browsing history 2. Preventing third parties, such as ad sites, from doing the same 3. Preventing search engines from assembling your "search history", and turning it over to the government. 4. Preventing sites that you don't log into from accumulating your local browse history over time. That's not perfect, but that's good enough for me.