Using terminology like "everyone" is the problem here. In these cases, there are a few outlandish instances that stand out saying "this is horrific", a few "this is bad" instances, some questionable ones that could go either way, and an incalculable number of "these are perfectly fine".
Brianna Wu saying "every man" is just like a racist saying "every Jew", and it also makes it difficult to take what are certainly very real issues seriously. But at the same point, she was able to point to 4 problems over a long career, not "every day I show up to work and am confronted by dozens of threats of rape, torture, or other sadistic behavior by unknown random people". And yet when someone told her that under no circumstances would they ever have sex with her, even after her death she responds by being afraid to go out in public after dark. That seems more like an "anti-rape" threat or a "just leave me the hell alone, it's never gonna happen" message than one to be concerned about.
Is she overreacting, perhaps. Are there more cases that she didn't feel inclined to mention, perhaps. Are the things that she mentioned "severe", yes. Should they be taken seriously, yes. But at the same point, they should be taken seriously against the individuals who levied those statements, not against an entire group. She accuses all men of being sexist, but in that statement she is herself showing that she herself is sexist of men and feels that she should be treated differently than any person regardless of gender.
Workplace problems should be taken seriously, and as the leader of the studio it is her place to handle them. If she isn't willing to do so, then she can either hire someone into an HR role or take her comments to an existing HR person to let them address it instead.