Moral of the story
Why is the "myth that web surfing is largely an anonymous act" still so "widely held" when, for the last decade or so, it has been so evidently false?
This articles illustrates a fact of online life: all web browsers have flaws, all flaws can be exploited. It also highlights the age-old issue of 'security versus utility' - for example, autocomplete might be convenient occasionally but storing unencrypted indentifying data self-evidently compromises security (even it's just YouPorn popping up as the missus starts to type in YouGov).
The moral is that *all* browsers are vulnerable to exploits if used with default settings so users should set them up to reduce exposure - turn off autocomplete, never store any unencrypted information, delete session data (including cache and cookies) on exit, never checkmark "remember me on this computer" features, don't bookmark any site you don't want the world to know you visit, and install reputable security add-ons such as NoScript for Firefox.
However, those precautions will only reduce, not eradicate, exposure - so don't be lulled into a false sense of security just because you've zapped a few cookies.
Anonymous online? Yeah. Right.