Let me clarify: If you think a post requires moderation, or isn't helpful or constructive, don't respond to it.
Mods also have discretion on when someone crosses the line with their response. Which is why warnings haven't been handed out, so far.
For example: If someone were to report a post, and then respond, they would certainly get a warning unless the mods had determined that the reported post did in fact fall in the guidelines subsequent to the report. If a post was a blatant breach of the rules, and someone responded, then their post would get modded and they might get warned.
If individuals were to propagate a discussion that was off topic for the thread it was in and perhaps breached one or more guidelines, the posts would be modded, and the individuals in question may or may not be warned.
Posting on this forum requires a certain exercise in judgement from members, sometimes. Situations will vary. The policies of the forum give members a certain amount of credit as to their ability to exercise that judgement.