The Onion, saying it like it is to its readers.

Yes and no.

While it's true that all websites (and TV channels) live on "eyeballs", by that logic CNN.com should have become a tabloid long ago. And their TV channel a "reality show" platform.
Whatever reasons have kept them serious all these years should still be valid. Different target audience (and different advertisers accordingly), less competition, professional pride, whatever.

and i agree, however on that same note (at least in the US when i was there and in panama where i live) i've seen a big decline in "serious" notices to open space for this kind of tabloid crap to go on air; slippery slope and all that.