Hello Colby!
One reason you may not want them enabled is the following:
Imagine you get a personalized URL for yourself as a lead, for example: www.mycompany.com/landingpage/ColbyD
You then give me that link because you want me to see how cool this page is.
I type it in my browser.
At this stage, the system thinks I'm you, so the data is skewed and the system doesn't register me as a new lead.
Hope this helps!
Louiza