Lil B: The TL;DR version of my post can be split up into three main points:
1. Exclusively relying on sending PMs or Forum-specific messages that are hard to find is not the best way of handling a site-wide problem – they're inherently too narrow to do any good.
2: A better alternative to the above would be to have a set of Image Submission Guidelines a la the Entry Submission Guidelines for every new image posted. In addition, pages that are troublesome should probably have specific warnings attached to them.
3: Barring repeat offenders from posting in certain Image Galleries (temporarily or permanently) may be a better way of handling the situation than the "SHUT. DOWN. EVERYTHING." approach. Granted, this would require either additional coding or moderating, but I think it's a way to avoid getting everyone's Jimmies Rustled.
And now, onto something different.
"WE take a hostile position because the USERS do it and quite frankly we’re sick of it. We’re just doing our job as mods, keeping things in order and making sure the site’s ok."
I completely understand your frustration, but two 'wrongs' don't make a 'right'. Have you noticed how, in the comments section of both of the "Childhood" pages and the "Alternate Universe" page, I was more combative against you guys when you were responding in a smarmy fashion to dissenters? Notice how I'm trying to write my posts in a much more diplomatic fashion here, given your more formal and respectful approach of addressing the problem (indeed, as the other users here are)? Attitude makes a significant difference.
"But after we warned users multiple times over the Childhood galleries, we were met by the entire comment section after our heads. We tried to explain but NOPE, WE AIN’T HAVIN DAT. We just get downvoted by a bunch of guys who don’t want to hear anything that breaks their little bubble, and then we get called draconian, people genuinely comparing us to Hitler, because we closed a gallery after warning them."
Could you clarify where this alleged warning took place? Because if it was in PMs, then I think you might have been setting yourself up for a disappointment. And if said warnings were so parsed out and obscured, then it's no wonder that users would be taken aback by what seemed to be a sudden lockdown of some of the most popular Image Galleries on the site – even if they decidedly went too far with comparing you guys to the subject of Godwin's Law. (Point 1 of mine applies here.)
"We tried to make them see what we were saying, but they didn’t want to hear it. I make no secret that I have nothing but contempt for the comment section, because this kind of behaviour is just horrible."
Again, I believe it's the way that you said it that people took issue with. I think the only true professionally-stated post regarding any of the decisions was the address that MScratch's made on the "Childhood" pages. Everything else seemed mean-spirited and directly confrontational to the audience (especially "Alternate Universe" – nobody really stated why the page was locked there, and just resorted to mocking anyone who liked the page). Giving vitriol toward the community isn't going to solve the problem, even if said community deserves it.
As for the flaws with the comments section, well, that's for another thread entirely.
TL;DR of the above wall of text: I respectfully disagree with a moderator, and raise a couple of counter-points/mention alternatives.