I was planning to start this thread myself OP. I think there's an interesting discussion to be had here, but it got lost in the judgement and combativeness of the last thread.
I agree with the "no choice made in a vacuum" position. No, nobody is forcing us to do these things, there's no law saying you must, and most people who don't will never even get a comment made to them about it. But when you are bombarded by media messages and surrounded by people who are doing it, it's very easy to internalise that. Especially if you're young. To quote another poster, we're like the fish who don't know that we're wet.
As a mother of 2 under 2 in my 30s I do basically no grooming. I don't wear makeup because I don't like the feel of it on my skin. I keep my hair very short so I don't have to style it. I don't shave as a political statement. I only wear comfortable clothes. On the main boards I frequently see women like me torn to shreds by posters claiming we've let ourselves go, have no pride, look dirty etc and with the heavy insinuation that it'll be our own fault if our partners cheat on us. I've got a wedding coming up and I feel hugely resentful that I "have" to buy a new dress (no I don't have to, but I know the bride well enough that she'll be pissed if I don't) when my partner can just stick on his old suit. I won't be wearing makeup because I don't own any, but I feel anxious about that as well. And wearing a dress with unshaven legs. The fact that I feel anxiety about existing in my natural state in front of (mostly) strangers makes me utterly furious.
As a teenager I felt enormous pressure to groom. I grew up during the peak of hairstraighteners and every sleepover at some point involved hair straightening. I had very very curly hair and got so much bullying over it and most of my time until I was in my mid 20s was spent hating my hair and trying to change it. I got bullied for being short and so wore high heels everywhere. I got bullied for being overweight (even though I wan't) and eventually developed an eating disorder that almost put me in hospital. Even after I recovered I was still very anxious about choosing clothes that made me appear slim. I've definitely had comments from sexual partners about my body hair - some complaining I had too much, other saying they preferred more. Most qualified it by saying "but its up to you of course" which doesn't really change the central message. I think that to say "there's no law saying you have to groom" is quite naive and ignores the huge pressure that lots of women do feel under to meet beauty standards and to hold their bodies up to the yardstick of male approval or peer approval. And for all the WATM talk of beards and top knots it isn't the same, men simply do not have the same appearance standards applied to them by society. And at it's core I think it's about 1) driving capitalism by seeing women as an easy target for the message "here's everything that's wrong with you, now pay us to fix it" and 2) keeping women too time and money poor, and too low in confidence, to fight back against these unfair messages. I honestly weep for the number of hours of my life, and the amount of actual money, that I've lost trying to meet beauty standards. Now that I've stopped I have more energy to redirect into other parts of my life.
So just as other posters are skeptical that anyone feels forced to do these things, I'm skeptical that anyone freely chooses to do them.