I haven't seen anyone on HN making the argument that artists shouldn't be paid, but I have seen several saying they don't think artists should control the pricing and distribution of their work. To me, that is the most fundamental part of copyright.
Gary Larson gets to say that his works don't appear online and the creators of Penny Arcade get to put all their work online and make money indirectly. The point is that they as creators get to choose.
We can go back and forth all day about if you copy a photograph without the photographer's permission you have stolen from them, but what you have done is violate his/her copyright.
In recent days, we've all been applauding Louis C.K. for the approach he took distributing his stand-up video. Some have been saying that all video content should follow that model. This ignores the fact that DRM-free online distribution was his choice, and every content creator should be free to choose what method works best for them.
I personally think the author should have included the cost in hours and education to get him to the skill level he has today. His cost of living vs. how many photographs of that quality he makes is also valid in how he prices his work. The point he was trying to make, though, is that this is not just a hobby for him and the idea that his work is not free is worth ranting about.