Re: Socialists ... complaining that breasts are sexist
Hello, radical Trotskyist here.
I think the confusion comes from the idea that socialists have an agenda for equality, and are wary that any differences between people, real or perceived, might be abused to cause harmful inequality,
Note, even the most radical socialist understands that inequality per se is not always harmful. If you have a million pounds, and I have a million and one pounds, that doesn't somehow mean you're going to starve to death, or even suffer in the slightest way, simply because I have one more pound than you do.
While there is certainly plenty of evidence that perceived or real (but trivial) differences between people do lead to harmful inequality (e.g. unequal pay for women that persists to this day, and more generally the so-called "glass ceiling" effect), the fact is that nothing we do will ever alter the fact that women do nonetheless have breasts, that the cause of discrimination against women therefore cannot possibly be addressed via those breasts, and that in reality the root cause of any and all inequality is an institutionalised problem, perpetuated by an extreme minority of powerful but increasingly geriatric dinosaurs, who thankfully will soon be extinct. And really, even they don't care that you have breasts, they only care about themselves, and see everyone else as subordinates, so they'd discriminate against you even (and probably especially) if you were a carbon copy of them.
Moreover the concept of "equality" is greatly and probably deliberately misunderstood by socialist-phobes. We don't want to create a planet of clones, we simply don't want people to die needlessly from poverty, while others lavish themselves in obscene wealth, deserved or otherwise. There's nothing in that agenda which suggests women aren't allowed to have breasts, nor that men are not allowed to enjoy them. I think you'll find that the rate of boob-related deaths worldwide is very close to zero, and certainly pales in comparison to death by poverty (e.g. 25,000 children every day, according to UNICEF).
If you're looking for the actual source of breast or any other sex-related tabooism, and indeed most forms of discrimination and causes of inequality, you need to look way over to the right, where the fanatically religious Conservatives live, and their equally contemptuous but more agnostic neoliberal counterparts.