There's a couple issues going on here. Number one is it's unique amongst the people who go to EFFs website cover your tracks. That's not all of the internet users. Hell that's not even most of the internet users. It's pretty niche community.

The bits of identifying information are the critical key here. 16 bits, 2 ^ 16.. 65,000 different possibilities. Each piece of information you give, makes it a little bit easier to track you. Things like language, time zone.. The more bits, the easier it is to identify you. The less bits, the more you blend into the crowd.

This is why multiple people, including myself, have talked about fingerprint.com they're professional service, who's targeting websites, who want to track users. So they're incentivized to track as best as able.

Even if you've got a great EFF score, you should always check fingerprint.com, to see if they can track you.