That's the thing, the backlash started when they announced an all-women cast, but it was like a school bus picking up more and more kids as it went along.
Some people were fine with them being women, but not fine with the specific casting.
Some people jumped on when they announced that the old Ghostbusters wouldn't even have cameos.
Or when details of the plot came out and it sounded like a spoof of one of those ghost hunter TV shows, which sounded like a really lazy premise.
Or when that really bad trailer came out. And a lot of people said it looked bad.
Because it looked really bad. It's correct to acknowledge that the people who got the ball rolling were mostly spurred on by misogyny, but at a certain point there were enough red flags that I think it was OK for regular Ghostbusters and comedy fans to raise an eyebrow without being lumped into the He Man Woman Haters Club.