"Congress tells Mozilla that blocking 3rd party cookies endangers children."

Link to letter: http://stanford.edu/~jmayer/content/Pompeo_Mozilla_Letter.pd...

Relevant quote:

    Internet industry publications estimate that Mozilla's overall share of the browser 
    market is now approaching 20 percent — a figure large enough that its 
    plans to block cookies would have a devastating impact on small businesses and wipe out 
    millions of life-saving AMBER Alerts and tornado warnings funded and delivered 
    to Firefox users by advertising networks. Concerns have also been raised 
    that the value of advertising in terms of lower prices and more choices 
    for consumers could be threatened if regimes are stood up that allow 
   conglomerates to have too much control over data.