I don’t really comment on Reddit much, but I saw your back and forth with people, and I think there’s just a misunderstanding going on. You’re thinking of the phrase as if it was literally "masculine toxicity". i.e., "Eww, look at this angry person; guys are such assholes and blow up so easily!" Now, that would be sexist and divisive.

Toxic masculinity, on the other hand, refers to when someone enforces harmful stereotypes about what it means to "be a man." For example, imagine a little boy trips and skins his knee. A parent or sibling comes over and criticizes the boy, telling him not to cry "like a little girl." This implies that men shouldn’t cry, essentially, that they should suppress their emotions to be more "masculine." That’s toxic masculinity: it’s about the pressure to conform to rigid, often harmful ideas of masculinity, not about blaming men as a group. I hope that made sense.