"toxic masculinity"

The claim is, as far as I can tell, that because men aren't "allowed" to show emotions or else they are considered less manly, they bottle their emotions up inside until they eventually explode with anger and become violent or something.

But here's the thing: emotions have no actual physical mass. Your mind is not a container that is accumulating more and more emotion-juice until it is released through the process of the person displaying the emotion they're containing. There's no scientific basis for any of this and seems like altogether an overly simplistic way of looking at psychology.

Your emotions are largely determined by chemicals in your brain, but it's not like they stick around if you don't act on them. You produce dopamine when you're happy, but you can't just store up a ton of dopamine by never smiling or laughing. 

In fact, there's even reason to believe that acting out on your emotions makes you MORE prone to act out on them in the future, not less. If you punch a pillow when you're angry, for example, you are more likely to react physically when you are angry than if you "bottle the emotion up inside"

http://www.nytimes.com/1999/03/09/health/letting-out-aggression-is-called-bad-advice.html

tl;dr By relieving aggression by screaming, punching, crying, etc. you are fostering these reactions to aggression, not subduing them.

So where then does this leave the problem of toxic masculinity? Is it just another buzzword for leftists to pretend to care about in order to get a gold star from their leftist friends?