The fact that Sia doesn’t show her face anymore – on television, on the red carpet, in publicity photos – seems to fascinate and offend people in equal measure. Put the words “Sia” and “face” into a Twitter search, and you’ll see a tidal wave of people who seem to view it as a personal affront that she won’t cast aside that wig and turn to face the camera. It is our God-given right to see her, after all, and she owes us an explanation.

Except she’s given us an explanation. Many times, in fact. This weekend, the latest version of that explanation trended on Facebook, when she told Kristen Wiig in Interview magazine: “I’m allowed to maintain some modicum of privacy. But also I would like not to be picked apart or for people to observe when I put on 10 pounds or take off 10 pounds or I have a hair extension out of place or my fake tan is botched.” We’re not really happy with this explanation, because picking women apart has become one of the web’s most popular pastimes, and her selfish attempts to retrain the focus on to her music have denied people the chance to indulge their hobby.

Daft Punk don’t show their faces. Neither do Slipknot, SBTRKT, Gwar, Lordi or Deadmau5. But they’re men, and so we accept their decision as a creative quirk – a sign of their individuality and artistic integrity. With Sia, though, we consider it our right to consume not just her music, but her entire physical being – to judge her clothes, hair, weight, complexion and age, to sneer and pass comment from behind our computer screens. We do judge men, of course – we’ll judge anyone audacious enough to put themselves in the public eye – but we save the full force of our cruel and personal vitriol for the women.

When I’ve interviewed female musicians, some have asked nervously which parts of their body will be filmed for the interview; other times their PR has emailed, asking if we could change the photo because they look “tired” or blemished. They know what’s in store for them if they dare to show flaws. When Buzzfeed posted an article entitled The 33 Fiercest Moments From Beyoncé’s Halftime Show, it got an email from her publicist saying: “There are some unflattering photos on your current feed that we are respectfully asking you to change.” Buzzfeed didn’t take kindly to this email, but in a time when the term “resting bitch face” is used for any woman not beaming benignly at every camera shoved in her face, it’s hardly surprising her publicist is so on guard.

The thing about Sia’s attempts to retain a modicum of anonymity that seems to mystify people, the reaction I’ve seen more than any other, is: “But, she’s pretty.” As if the decision to conceal herself would be entirely justified if she were unattractive, that in that case it would be only fitting she hide her face, preferably with a paper bag. No one wants to see an ugly woman, apparently. But a not-hideous pop star reluctant to be picked apart? It’s just sheer madness.

But even if this insulting logic could be taken seriously, we’d still be forgetting one thing. If a female musician is willing to embrace celebrity, and wear nice clothes for us while she’s carted along to premieres and awards shows … well, then she’s just showing off. It’s one of the Daily Mail’s most beloved phrases. The day I write this, Mail Online carries the story of how Rihanna “shows off HUGE cleavage in a low-cut LBD”. Self-confidence, after all, is one step away from arrogance, and therefore should be heartily discouraged. “You don’t know you’re beautiful,” sing One Direction to a generation of teenage girls. “That’s what makes you beautiful.” If you’re ugly, feel free to hide your face, but if you’re attractive, you better damn well pretend you hate yourself.

It hasn’t always been quite this way. If you watch an old episode of Top of the Pops, you’ll notice something strange about the women who used to perform. The vast majority of them look bizarrely normal. Sure, there was the iconic style of artists like Debbie Harry and Stevie Nicks, but it wasn’t all their career was pinned on. The 1980 edition shown on BBC4 last week showed such resolutely normal-looking women as Marti Webb, the Dooleys and Fern Kinney. None of them looked like models, but back then, having extraordinary good looks wasn’t considered necessary for a woman who wanted to be a mainstream pop singer: beauty was appreciated, but it wasn’t demanded. And there wasn’t the same “circle of shame”-style desperation from the press to reveal and then mock women’s flaws, punish them for being confident.

As for the argument that Sia is just drawing more attention to herself by hiding her appearance, she would disagree. “I was at Target the other day buying a hose,” she told one interviewer – rubbing our faces in her showbiz lifestyle once again – “and my song was on the radio and nobody recognised me, and I thought: OK, this experiment is working.”

Sia does not owe us anything. In buying her records, we haven’t bought the right to see her face. So let’s stop demanding an explanation, and start focusing on creating an environment that doesn’t systematically shove female musicians, smiling meekly for photographers as they attempt to look both beautiful and humble, between a rock and a hard place.