Yes it was the Brats thread.
For anyone who didn't see it, a brief synopsis:
OP was indignant that office workers and sixth formers from a 'nice leafy suburb' were wearing their ID/access lanyards into a local convenience store.
She felt they were 'lording it' over the shop staff and flaunting their privilege by showing that they either had a (better) office based job or were still in education at 18 - an opportunity she feels has been denied to most shop workers . She called it 'grossly insensitive' or something.
She had a lanyard herself but wouldn't dream of wearing it in front of retail staff out of 'utter respect' for them. 
Bonkers as conkers. And incredibly patronising.
I have no idea whether it was a genuine OP from a person with a very weird outlook on life, or whether it was made up bollocks done purely to wind everyone up. I suspect the second. But then I suspect 50% of the threads that make it into 'active' are based on lies or contentious opinions to some degree or another.
I'm not saying it was the most hilarious OP in the world, although it was amusing in a bizarre, WTAF? kind of way. But it had the potential to be a very funny thread had it been allowed to continue.
Either way, it was doing no harm and it sparked some interesting responses - not least an opportunity to challenge the outdated preconception that people in hospitality or retail don't have much in the way of qualifications. Many of them are graduates these days (which is another discussion altogether) but a worthwhile discussion could have come from that.
Anyway, my point is that MNHQ seem to have become frightened to let anything stand if someone decides they want it removed, sometimes for the most spurious reasons, or if there is even the teeniest possibility that someone might decide it's offensive.
There are obviously quite a few snitchy little teacher's pet types who love the thrill of spotting something 'off' and reporting it, just so they can say 'I knew it' and get a smug little glow for the rest of the day when it's deleted.
Nasty, highly offensive trolling, fantasists posting about ficticious tragedies etc, then yes of course, report it. But we've reached a point where just having a weird or obnoxious opinion makes a thread worthy of deletion and it's got to the point where some days I have as many deleted threads in my 'Threads You Are On' list than undeleted ones.
In ye olden days of MN barely any of them would have warranted a deletion and it was common to be refused a deletion of your own thread unless your life was literally in danger over it.
People knew they had to take responsibility for what came out of their mouths. If you asked 'AIBU?' and were unanimously YABVVU, then you had to suck it up and learn from it, not run to teacher complaining about the mean girls. And the thread stood as a lesson to others who might want to pull the same sort of shit.
These days it's all 'not in the spirit.' 
As an example of how much MN has changed, a quick look in Classics and you find a post 'I pooed on my skirt at work today. I am not the poo troll.' and then a lengthy description of the poo accident followed by pages and pages of poo/period accident stories.
Today that wouldn't make a full page of posts before it went, let alone get into classics.
There is another thread from 2018 called 'Expats, tell me what aspect of your new country do you find strange?'
40 pages of expats talking in depth about the cultural norms of their adopted country (including the UK) that they find outdated, sexist, appalling, funny or plain weird. And not one deletion as far as I can tell. Could you even imagine that now? That thread would be reported to fuck for racism and xenophobia. The risk of leaving some of the comments in place for someone to possibly become outraged over is just unthinkable today.
The Yoni massage would not have made the cut.
Neither would 'I'm looking for a governess. May I look here?'
That one properly took the piss out of what I think was a genuine OP. Brutal but funny. These days that would be considered 'not in the spirit. our job is to make parents' lives easier blah blah.'
And this one? No chance. Instant deletion.
www.mumsnet.com/Talk/mumsnet_classics/1055369-LOOK-READ
Yet there is barely a day goes by when I don't read something in Relationships and AIBU and think 'that didn't really happen though, did it?' But because the OP is telling some tale of woe it's left to run and we have to give the OP the benefit of the doubt even when most of us think it's horseshit.