Time for an Internet Audit Bureau for Online Subs?

Jupiter’s David Card, reflecting on the recent AOL loss of 846,000 subscribers, wonders why there isn’t an audit bureau for web subscriptions:
“… The online industry needs an equivalent of the magazine industry’s Audit Bureau of Circulations, or else has to pay more attention to the ratings companies, a la television. As for Wall Street – well, they should have been using a more sophisticated tracking system all along, say, revenues in combination with time spent or unique visitors from comScore Media Metrix or NetRatings.”
(link via John Robb)
This is an idea whose time is going to come as the paid content model-and the growing number of “You have to subscribe and give me your name to get these RSS feeds from me” sites continues to grow.
Slightly off-topic: Do Jupiter analyst blogs have RSS feeds? Why the heck not?