What else would you like it measured by? Paid subscriptions? Because we all know how that goes.
The breadth of online journalism we see today is precisely because of those ads everyone claims to hate. It allows anyone to quickly join the pot and lets the market decide their value. Without ads we'd be stuck with the 4 fuhrer model we had for the last 100 years.
Because a journalist needs a minimum of $50 a day, it's a hit based business, and readers are fickle. Everything you say must be in complete agreement with their world view to get a donation. One mistake and they're gone.
Also, it's been tried before and has failed every time.
A subscription based donation system might still work though.