I don't see the issue.
What I find ironic, is how much HN despises anybody who tries to make money from their work. There's a bizarre ideal here of the selfless internet "Mother Theresa," who exclusively works on open source projects and only shares things with the world out of passion.
You could spend 3 years compiling research on an extremely valuable topic and publish it for free...but if you put a newsletter sign-up form on the page, somebody here will complain about it.
Strange, considering HN is hosted by an entrepreneurship incubator.
I think that comes from biased expectations. Any time I see an ad for something promising to be high quality I am usually disappointed by the actual quality. Conversely when a free thing is linked on HN and upvoted to the front page it is very likely to actually be high quality.
Therefore my biased assumption for links on HN is that P(high_quality | asks_for_money) < P(high_quality | totally_free)
I haven't recorded enough information to know how badly biased my intuition is.
I have a freely accessible blog with 3500 subscribers, there is newsletter sign-up form at the bottom of every single article, and I haven't heard a single complaint about it ... people who actually like to read are a lot more reasonable than widely expected.
Or perhaps the prevailing culture on HN is very, very different from the wider world.