I haven't read more than the last few posts, but I thought I'd throw in my two cents.
I have no doubt that sexism is a factor in politics, as in most factors of life. But I do not think that's not the main reason Warren's campaign failed, or even a significant factor. I see it more as a combination of several factors:
1. She started out progressive, and pivoted more to the center. In particular:
2. She backed off on Medicare for All, offering a convoluted plan.
3. She's a quintessential New England white academic, so had limited appeal to people of color and working class whites. In other words, she's a Chardonnay liberal.
4. She back-stabbed Bernie with a rather dubious accusation of sexism, as well as other slights on him, despite him treating her with respect.
5. She has a long history of little lies, which damaged her credibility.
6. She hired Clintonian strategists and began taking Super PAC money with a hidden donor list, while still Bernie and others of PAC money.
Four years ago, like Bernie Sanders, I wanted Warren to run. I thought she was intelligent, balanced, and progressive enough to excite the left, but not so "pinko" to scare off moderates. When she didn't endorse Bernie, especially on the even of the Massachusetts primary which could have strengthened his candidacy greatly, I started having doubts. Those doubts have increased over the last year, for the reasons above.
The fact that she has not endorses Bernie, and instead still criticizes him, confirms all of the doubts that progressives have about her. Both that she's a lukewarm progressive, but more so that she would let her political aspirations and wounded ego damage the progressive movement. I'm not totally closed to her; maybe she's playing the long game and wants to be Bernie's or Biden's VP, and if the latter find a way to institute more progressive policies while Biden plays the increasingly senile Uncle Joe figurehead. But that's a charitable reading of her.
In short, her fall is easily explainable without even touching on sexism. Or rather, the element of sexism that is a major factor is her disingenuous levering of identity politics against the guy who should be her strongest ally and has treated her as a friend. I mean, that moment when she chastised him on a hot mic and wouldn't shake his hand was just deplorable. She dug her own grave.