The track blocking add-on is a very elementary method - it is in fact the tip of an iceberg.
It is important to highlight that extends far beyond Marketo, Google Analytics, AWStats, eLogic, ShinyStat, SiteMeter, StatCounter, W3Counter, W3Perl, Webalizer and Woopra among many others.
Modern tracking relies on JavaScript. Savvy users choose to enable and disable JavaScript as needed. That is the reason tracking becomes discontinuous. One typical evidence is the activity log in Marketo: you would find Fill Out Form without Visit Web Page. From the practical standpoint, if a form is hosted on a landing page, tracking would display both.
Privacy is a cat and mouse game. Blocking tracking is just one basic technique. Anonymous browsing is far more powerful. It relies on multiple layers of proxy servers. To put into perspective, a user based in the US, running Chrome on Mac OS X may be tracked as French running Firefox on Linux. A further step, combining anonymous with disabled JavaScript, would suppress that all.
I would suggest a simple and very quick test: visit http://www.hidemyass.com, visit a landing page and fill out a form.
Locate the lead and review the activity log. Review the stats if you have Google Analytics and/or any of the tracking tools mentioned above. The results will be consistent.
Tor is the most advanced and effective privacy protection. It was originally developed with the U.S. Navy in mind, for the primary purpose of protecting government communications. It consists of a network of virtual tunnels.
Mac OS X, Linux and Unix users have vast resources within easy reach. It is fair to argue they are a minority of desktop users. However it makes sense to consider most mobile browsers run on iOS (Unix-based) and Android (Linux-based). There are anonymising browsers for both platforms. I am a native Unix user, back to early 80's. I was used to access the Internet before it became commercially available. Privacy was not a concern at that time because it was a closed and very controlled environment. I decided to remain protected, the reason I am so familiar with a range of techniques.
In summary, privacy is a challenge for the while advertising, CRM and Marketing Automation industry.