Maybe they do -- it depends on who's judging. To use Max's example, let's say I am casually interested in owls. Seriously, there are such people. I'm 60, I am on the internet but am somewhat uneasy with how to use it, and I like owls. Somehow, I find Max's owl video site. I like it! Maybe I even see an ad and click and buy. Maybe. But to me, finding the site and being entertained by his collection of owl videos -- that has value.
I do think there will be 300 youtube aggregated owl sites by tomorrow 9 am though.
Best to diversify and do one on whooping cranes instead.
Most sites and tools I use every day are filtering tools. Techmeme is another great example.
It is true that a purely automated owl video scraper wouldn't be as good and one that was even cleaned up for five minutes a day, but that wasn't the suggester's point.
That is beyond, and because of, the aggregation. What is created is new and more valuable than the original posts, or even the aggregation thereof.
Google news is a good example, no one could really say that having all that article discovery and grouping was providing no value. Google scholar provides no content by itself but is very useful.