Only boring humans are just the product of the content they consume; interesting people have concerns about relationships with other humans, organisations, resources, threats and opportunities that come from being an entity living in a world full of things they don't control and things they'd quite like to control. It's also fairly easy to identify artists who have done nothing but look at other art.
Hayao Miyazaki once said "Almost all Japanese animation is produced with hardly any basis taken from observing real people, you know. It's produced by humans who can't stand looking at other humans. And that's why the industry is full of otaku!" While I'm not actually a huge fan of his work, it's easy to see where he's coming from when you see the likes of "In Another World with My Smartphone" or the hundreds of other trash light novel adaptations. They're clearly fiction being produced by people whose lives are nothing but consuming other fiction, and all they can do is reference that. They have nothing to say.
For another example, there's a huge number of 20th century war films. They weren't made because their creators had read a lot of Wikipedia articles about how destructive wars were becoming. The likes of Platoon are a product of mortal fleshbags who actually saw combat and genuinely feared for their lives. Dr. Strangelove was created by people who had a genuine belief that they were at risk of being annihilated in a nuclear fireball.