The "no snitching" culture is shitty, even on forums. On a side note, it's hilarious how many times throughout the years I have seen anti-black posters complain about the "no snitching" ethic while holding that it's wrong to "snitch" here.
As a poster, there is an overriding disincentive to reporting posts. Mods (not all of them or even a majority of them, obviously) share information with regular posters about which posters report people, and this information gets around in PMs. If it ever becomes public, the person who consistently reports posts that break the rules is harassed endlessly.
I report a post maybe once a year on average (less counting my entire time here), most recently for somebody who has been spreading lies about me for years. What stops me from reporting more posts is not some personal no snitching ethic, but because 1) I enjoy fucking with them right back, which means that it would be unethical to report them, 2) Apathy, but also 3) Because I don't want to be on "the list" because it would result in me being harassed, which just isn't something I feel like dealing with.
If there was no stigma, I would probably report several posts a month in here, because it would be good for the forum. It would be very easy to report 50 posts a year without ever making a report that is borderline or inappropriate. There is a diffusion of responsibility in a no-snitching culture which polarizes people into "snitches" and "cool." The poster who chooses to use the report feature as intended will end up with a number of reports that, if made public, would cause them harassment.