The most reliable form of web traffic measurement is reported ad impressions from a reputable 3rd party like DoubleClick. They do a fine job of eliminating bots and spiders (unlike log files) and only meaure an impression once an ad is served.
Eliminate pop-ups and unders (which our sites do not take) and one can get a true measurement of traffic. If you have on average 2 ads per page on your site and monthly ad impressions served is 100,000, then you have 50,000 monthly page views. Sure you are still in effect undercounting when you factor in ad blocking, etc....but what do investors and VCs really care about, the ability to generate revenue. Ad impressions are the true way to factor that in and provide a fair measurement of traffic.
ComScore and Neilsen are antiquated measurements of traffic, how many Slashdot users out there would download ComScore software to be a part of a web "panel"??? I don't think many of us would do that.