A broken masquerade and a full involvement of modern humanity in defending itself from outsiders would be a net benefit to basically everyone. And that's before you consider aliens in the setting.
I doubt it. Humanity has come a long way, but every bit of progress can be stripped away with the equivalent of a cantrip by anything capable of magic.
There's also the matter of how physical law doesn't apply the same way in the nevernever. The deeper you get the less likely it is for technology to work. The outer gates aren't a friendly place for this sort of thing.
The best evidence of that would be the fact that no one uses modern weaponry there. Senior council members who use guns on earth don't bother carrying them at the gate, and the fey aren't setting up machine gun nests.
Winter does make mistakes, but they aren't so stupid that they'd fail to pick up on potential tools. They certainly aren't shy about stealing other ideas from mortals.
A broken masquerade, properly handled, would be good for making mortals more capable of defending themselves but it isn't a cure for all ills.
For this specific problem Molly's hell is a better solution. Our own demon planet should be more than enough to let us slip into their role and then displace them politically.
That way we can force reforms without causing a supernatural world war or getting earth tentacled to death.
Which we should at least start before the masquerade falls if we can manage it, because trying it afterwards is going to be significantly more complicated due to the mortal world melting down.
Thats so stupid tho, there literally millions of adult humans trained for war that you can just hire for money, there is literally no need to send any children there. Ita fucking stupidity. Mab dies for it.
It's unlikely that Winter is actually sending the kids they take into battle after two weeks of boot camp. Because that's just stupid; they've been fighting for ages and expect to be fighting for ages more, training their troops until they're at their maximum potential is a basic planning thing.
Winter is cruel, callous, and sadistic. They're at best an organization that needs serious reforms* but anything outright obviously stupid is suspect to me.
Unlike a human autocracy, Winter's highest focus is directly on their stated goals. Mab values literally everything below her duty because she isn't capable of doing anything else.
On the hiring millions of adults thing; that's only been an option post Industrial Revolution, and money probably isn't going to cut it.
I'm pretty sure that once you go past the gates you aren't allowed to go home again unless you're a mantle bearer with special resistance to Outsider memetic hazards.
This isn't meant as a defense of what they're doing, just as a clarification on what exactly they should be accused of. Winter sending sixteen year olds out to stab outsiders with swords after a quick hit of magic and two weeks of training is a waste of everyone's time independent of any moral judgement.
Taking them to brainwash for four years or so before sending them to kill their enemies at least makes sense even if it's still horrible because making and using indoctrinated slave-soldiers is self evidently awful.
* In the sense that some of their leadership needs killed so they can reform into better people through the next mantle bearer. See redcaps and Meave.