I've been lurking on S&B for about 15 years. I don't post much: I don't live in the UK so haven't the same shops or the same style as many posters. I still come on here quite often, though. I just skip threads that don't interest me, and keep an eye on how UK MNers' fashion focus differs to the way things are where I live. I find it really interesting to see how attitudes to trends vary between countries. There are also a few posters whose opinions I value and whose style I like, even if it wouldn't suit me.
I don't really miss some of the old threads mentioned here, as there was an unsettling focus on thigh gaps and thinness from some influential posters. But there definitely was more of a "club" feeling before, simply because there were fewer MNers, fewer threads and posts and MN's demographic was more homogenous.
S&B has changed as regulars have grown a bit older, so their bodies and attitudes are not quite the same, and as MN has grown so much bigger. Cod used to find affordable, wearable clothes and lots of people followed her suggestions, but now there are fewer such clothes out there and more diversity on MN, so less scope for "the top" or "the dress" to go viral, (and no one would dare be as scathing as Cod was).
WFH and Covid have led to a dearth of satisfying threads, like the poster who was looking for a dress for her Scottish beach wedding, and I think that's been compounded by (as lamented on S&B) the limited availability of flattering, well-made clothes in OK fabrics and at affordable prices. Some of those issues will begin to fade when travel, parties, events, etc. gradually restart, but I wonder whether the latter problem isn't here to stay.
I agree that the "who cares what people think, wear what you like" posts are a bit distracting on S&B, but they are perhaps a reflection of how more people feel free to try and move away from norms and expectations about how women have to dress/look. That in itself is kind of interesting...as is the changing attitude to grey hair, perceptible on these boards.
Splitting S&B in two isn't a workable idea, because lots of threads wander a little, which is no bad thing, and there is no clear cut-off. OPs don't always provide defined criteria for what they want/like, so you get people making suggestions that don't suit them but do suit other people, in terms of style, budget, etc., and it would be a real shame to stifle that.
I agree that the "guess my age" threads are grim. They reinforce the notion that looking your actual age is somehow a bad thing, and I wish MN would pull them as soon as they appear. No one in their right minds would wander round a park, pub or station asking complete strangers to guess their age, and it never ends well on here.