This is a time to celebrate. At last, a woman leads a major US party to fight for the presidency. It’s been a “long, long journey”, as Hillary Clinton said in her strong speech at Brooklyn Navy Yard as she crossed the line – and that’s the trouble. She’s not new: we know her too well in an era where insurgency and novelty trumps experience.

But if she wins, what an added bonus that, as the first woman to enter the White House, she will also step through the door as by far the most qualified and experienced arrival there for generations. So often the White House has greeted the frighteningly ignorant and clueless as the new master of the universe. As a former secretary of state and a rare woman in an 80% male senate, this first woman would also be the safest pair of hands in decades. Unlike most, she knows how to wield the power levers, insofar as the insane US constitution allows any president to carry out their manifesto. To get there, she will have seen off Trump, the most dangerous, reckless contender ever to win a party’s nomination.

But among too many who should know better, her success has been greeted with a jaundiced yawn – or outright contempt. The Guardian’s debate yesterday, asking if she had finally shattered the glass ceiling, was met with a shower of dismal negativity. But that’s normal, as she arrives in pole position accompanied by a searing firestorm of abuse from both Bernie Sanders and Donald Trump, with hotter blowtorches to come. This is where her experience counts: she has grown the hide of a rhinoceros after an entire political career battling contempt.

Why so fierce, so unreasonable, so vitriolic? That’s the political time we live in – but there’s much more to it in her case. If you are naturally left of centre, especially if you are a woman, yet you find you instinctively dislike her, ask yourself why. There may be some good reasons: she’s not as radical as Sanders; she is not a natural rabble-rouser at rallies; she is the wife of a past president; she’s called “robotic” in her careful choice of words; and as a flesh-presser she warms the cockles of few hearts. After Barack Obama’s effortless charm and sublime speech-making, she is bound to seem leaden-footed in comparison.

But consider this. Clinton is not some token woman who has inched into place by offending no one. All her life she has fought the feminist cause, for abortion and for equal rights, fearlessly, right from her college commencement speech. “Fear is always with us but we just don’t have time for it. Not now.” Compare her to Margaret Thatcher, who made her way in a man’s world by refusing ever to espouse women’s causes, a queen bee who kept women out of her cabinet so she could stand out alone.

In politics, feminist women are mocked and scorned, more than those who avoid women’s issues. The comparison here at home is Harriet Harman – “Harperson” – who has had the same treatment ever since she was first greeted with snorts of derision as a pregnant figure of fun rising in 1982 in a 97% male House of Commons to demand holiday childcare in her first question to the prime minister. Thatcher replied: “No, I do not believe that it is up to the government to provide care for schoolchildren during the school holidays.” Like Clinton, Harman never gives up, winning battle after battle, not just on childcare and nurseries, women-only shortlists and domestic violence laws, but also on the minimum wage, which affects women most – and much more. But like Clinton, she’s not loved. That wall of noise from hostile men warps many women’s perceptions too.

Why? Another force counts against Clinton (and Harman). If women of the left do break into the bastions of power, the sisters often view them as sell-outs to the establishment, as if permanent outsiderdom and victimhood is the only true mark of feminism. Success just isn’t part of the script. To join the establishment isn’t the point, though that’s the only way policies get changed, good laws passed and funds spent on what women need. That’s a wider disease of the left among Sanders and Jeremy Corbyn supporters too. To win is to lose.

Surely now the presidential choice is so brutally stark, all Democrat-leaners will warm to Clinton. Rarely has any candidate so deserved their place. Outside, the world looks on aghast at any possibility America could choose a racist, sexist brute over a feminist with a long track record of standing up for the right causes. For the young, she’s been around all their lives, not new enough to be exciting. Yet the prospect of a strong women leading the world should be a beacon of hope to women everywhere. And if you want a reminder of what women like her are up against, just read the comments that will no doubt follow this.