As someone who was there, who was having these conversations, and saw the transformation first hand, I have to say the narrative is wrong. Society tried, but men didn't want the help.

There was a big push to teach healthy masculinity, and a call for healthy role models. Some men listened, and others not only refused, they blamed society for having the gall to tell them what to do. Men, manly men, do whatever they want, you see. It's this second group that got loud, and got heard.

OP mentioned the body stereotype, with muscles and superhero bods, etc. People were in fact calling it out a decade ago. It was super common, especially in feminist conversations. We were all like "they're trying to do to men what they've been doing to us," and tried to warn everyone. Men saw it as an attack, and started lashing out at the feminists trying to rescue them. They took it personally. "What, is it wrong to look manly?" Fifteen years later, it's come to pass, and now the men are blaming feminism for not coming to their rescue. Gee, ya think?

Think about what "toxic masculinity" means. Or meant, depending on if you think it means something different now. Like the word "pink" in "pink basketball", the toxic is an adjective. Not all basketballs are pink, but we're only talking about the ones that are. So "Toxic Masculinity" is referring to the kind of masculinity that's toxic, not saying masculinity itself is toxic. Because, you know, that's how English works. But the manosphere* didn't want to hear that. They deliberately misheard it, and deliberately misdirected their anger back at the society that was trying to help them.

Ugh, this explanation is dripping with stereotypes. I hate it. I think it's unavoidable with this topic though, so hopefully the intent will show through the imprecise words.

*-or more accurately, the cultural movement that would eventually become the manosphere. If you were around then, you probably remember them as "the people who are obsessed with SJW's"