The problem is, I think, that every time someone lands on one of these sites it enhances that site, whether it be for actual $$$ or just their position ranking in search engine optimization algorithms.
I'm pretty sure you're correct about that, and it's definitely something that goes into the equation. It's all where you draw the line, I think - example: I won't EVER pay for a subscription to NYT, but I'll look at free content from them. To me, it's just so important to get a fix on what "others" are thinking, reading, hearing, etc.