The answer is that Non-constructive comments contravene the Code of Conduct which governs the operation of the forum. https://forums.flightsimulator.com/faq#heading--spam.
The moderators here are all volunteers and part of the community tasked with upholding the Code of Conduct. There are not many of us spread across all time zones and there can be thousands of posts in a day. We rely to some extent on members of the community letting us know via flags or private messages to the moderator team to give us a heads up. Overall we try to be balanced and fair but in the end we will take action where the code is broken