If it helps, you can think of it like rude/abusive flags, which you don't raise on an otherwise acceptable answer that uses curse-words. Those can be fixed. And you don't raise rude/abusive flags on an answer because a user posted a rude comment. And you don't raise rude/abusive flags on an answer because a user took some retributive action, like voting to close the question because their answer wasn't accepted. All of those subtle cases require custom flags.
@Moo Blaming the tools is reaching a misleading conclusion. Yes, there are practical limitations in the moderator tooling. It's also true that moderators sometimes make mistakes, like overlooking things or simply clicking the wrong buttons. But that's not what happened here, and chalking it up to that mean that you miss the lesson that we are trying to convey, which is that red flags should not be raised on posts with subtle/correctable issues.
@Moo I mean... you are saying here that this happened to you before, and yet you did it again, expecting a different result? And you think that that is the moderator's fault, rather than your fault? This is difficult for me to understand. You have received feedback before (in the form of declined flags) that subtle, SE-specific problems (particularly fixable ones, or even ones that need to be handled exclusively by a moderator by, e.g., sending a message to the user) like undisclosed affiliation should not be flagged as spam. And yet you paid no attention to this feedback, simply repeating the behavior again. In response, you got the same feedback, and you think the problem is the mod who is giving you consistent feedback?
I do agree it is unfortunate that prolific flaggers who are getting feedback on their flagging are more likely to encounter a flag ban than occasional flaggers who raise flags that are just blatantly incorrect. But that's a system-level problem, which moderators cannot fix.
@Moo This gets dangerously close to complaining about specific people. I understand that you were upset, and it's totally fine to ask or even complain about something that you feel is an injustice. But please be careful in the future not to personalize it. You'd be surprised how much harmony there is among SO mods, in terms of us agreeing with each others' actions. It doesn't always happen, but it does more often than not.
@Moo Decline in this case is like saying "you raised the wrong type of flag on this post". Which... is what you did. Decline can either mean "this shouldn't have been flagged at all" or "you flagged this for an inappropriate reason". Sometimes moderators are generous in not declining for the latter reason, if we think that the flag was raised in good faith but we decided to handle it in a different way. But for active flaggers, it makes sense to me to decline when the wrong type of flag is raised, because this gives the flagger the chance to revise their flagging choices.
It sounds like you perhaps thought that as long as someone raised a custom flag, then others can go ahead and raise red (spam) flags. That is not correct. If it's not blatant, obvious spam that can be handled by anyone (non-moderator users), then it should not be flagged as spam.
@Moo Yes, that's completely normal and expected. Spam flags should only be raised on posts that are obvious, blatant spam. Undisclosed affiliation is a more subtle rule that should be handled with custom flags and more care by both users and moderators.
!!/report stackoverflow.com/a/79402512 "Very likely undisclosed promotion. (Video is brand new as of posting this answer. I couldn't be bothered to verify PII matches or anything like that.)"
