Signal and information are not grass.
Grass and property require upkeep. Radio waves and electromagnetic radiation do not.
I don't want your dog to piss on my lawn and kill my grass. But what harm does it cause me if you take a picture of my lawn? Or if I take a picture of your dog?
If I spend $100M making a Hollywood movie - pay employees, vendors, taxes - contribute to the economic growth of the country - and then that product gets stolen and given away completely for free without being able to see upside, that's a little bit different.
But my Hacker News comment? It's not money.
I think there are plausible ways to draw lines that protect genuine work, effort, and economics while allowing society and innovation to benefit from the commons.