I've thought about this, but I thought it was my thought. Without the internet, I could have likely continued walking around thinking it was an original idea.
I think in order to make something yours, even if it's a thought others have had before, you take the whole of something, wrestle with it internally, then pull it apart and put it back together. There will inevitably be parts of the whole that you leave by the wayside, and other parts you stay with. Since you are a person with unique experiences, what remains - when combined with the viewpoints that come from those unique experiences - will effectively be yours.
Reflection time is hugely needed. But I don't know that it's hugely important to distinguish in that time between reflection on your "own" thoughts and those that originated in some way outside your head, because at some level it's impossible to make the distinction. You'll need a huge base of exposure to other people's ideas if you hope to assemble them into a new and interesting combination of your own.
[0] https://www.elfproductions.com/news/2017/6/25/applying-imagi...
Art history is riddled with such free-thinking products. To an extent punk is derived from the avant-garde movement.
Closer to home, there wouldn't be data science without statistics though you can find data scientists that don't necessarily grok statistics.
Same with full-stack JS devs that skimmed CSS and/or web design history because doing everything in JavaScript in the name of reusable components and reduced mental overhead is what Facebook does, so it applies to every case given the weight of the benefits (without taking app weight and projected expansion into consideration).
This is IMO one of the reasons we get so much cargo-cults and tribalism around software development overall. Too much detachment in the name of abstracting complexity away.
for the entirety of human history, we've been growing by collecting and synthesizing the wisdom of others that come before us: standing on the shoulders of giants. we are surprisingly incapable when working alone. for instance, there are numerous examples of eruopean explorers starving or dying of easily preventable causes in the Americas, in the very spaces where natives had been living for tens of thousands of years. they weren't stupid, they just didn't have the foresight, or cultural knowledge that the natives did. [0]
There's the idea that "everything is a remix" [1], popularized by Kirby Furguson. he essentially states that we don't have much (if any) original creative thought, and that most "creative" ideas are just remixes of other ideas. this goes back all the way to prehistory and especially applies to traditional myths passed down orally through generations: see the numerous flood myths prevelant in almost all societies.
what I'm getting at is that we are not inherently creative beings, we don't do especially well when coming up with completely novel ideas. what we ARE good at is learning, synthesizing, and remixing.
so I'm not entirely sure that our "moth to an interesting article" behavior online is really that bad for us, I think its more the state that we are in when we do that - skim, go 'oh that's neat' and move along.
[0] The Secret of Our Success by Joseph Henrich
I've drastically reduced my usage of social media services not for productivity reasons, but because I'm not comfortable with the insanely detailed profile I end up revealing.
For example: a real conversation has so much more depth because of facial expressions, change in voice, and so on. An emicon can't replace that.
Social media & modern recommendation engines have made thinking other people's thoughts seductively easy. Modern apps give us an infinite feed of semi-engaging thoughts to consume in any media we want - from tiny text messages on Twitter to 30 hour audiobooks on Audible. Movies on netflix, short movies on youtube, not to mention podcasts and so on.
And no question, lots of it is fantastic content! Its just - all the things I'm most proud of doing have needed way more of my own thoughts than the thoughts of others. At least 10x as much time genuinely thinking and creating vs time spent in consumption mode. But with so much great content out there, I doubt many of us take the time to do enough thinking. I know I don't, and it chills me to the core.
So I'm not surprised that taking a walk - an activity during which its hard to consume the thoughts of others - leads to an increase in creativity. I would expect that anything which disconnects us from recommendation engines and notifications would be rehabilitating for our inner voices. And what is creativity but our inner voice given form in the world.