It's not difficult at all, these companies just have no reason to do it that way. They force you to agree to their terms before you can use the website at all, which means they're in a much better position to make demands. We can't counter with anything, it's just "agree that we own this copy of your content".

And most of us agree to it because we have no way of knowing that someday our content might actually be worth something.

Most of modern civilization wasn't built by the current S&P500 — most of them didn't exist 50 years ago, let alone 100 — it was built by humanity, collectively, over thousands of years.

That fact won't stop any individual or corporation from trying to claim absolute dominion over the entire human population, all derivative works and resources, or the rest of our descendants futures, for all eternity.