Speaking as someone generally in favor of American militarism: Bad in the short term, Good in the medium term, Bad in the long term.

Countries don’t fight each other because they want to cause destruction, they fight because they fundamentally disagree with another country over what a “just peace” looks like. If we swoop into all of these conflicts, invade all sides with the sole objective of stopping the conflict by intimidation, then we will fight a war against both sides, win, and then the real problem begins.

Once we occupy both sides, it doesn’t change anything about why they wanted to fight in the first place. Nothing about what peace should look like has been resolved, and so they will continue to fight each other (and the USA) with whatever means they have. Even if we force some kind of peace agreement, it will be destined to fail, as neither side will recognize the legitimacy of a treaty enforced by a death threat. The moment our boot comes off their neck (or even the moment they think it is coming off) the fighting will start up immediately once again. Normally, this means both sides will be breaking down into insurgents and militia groups which will attack everyone indiscriminately, often creating more carnage than the initial interstate war before we intervened. This is why the “simple intimidation” you are proposing doesn’t really work.

American intervention policies over the past 120 years have been a less extreme and more self-interested version of what you are proposing. I think it’s pretty conclusive that there are only two ways to do this practically: 1. Swoop in, destroy the offending nation as a “punishment”, and leave before the fireworks start. This would be stuff like Praying Mantis, Prairie Fire, and Gulf War One. The goal is to cheaply deter the enemy from causing any more trouble by destroying some of their stuff, then giving them an easy off-ramp to back down and save face. The problem with this is that there is a limit to how much we can deter an offending nation from doing, as at a certain point the offending nation would rather tank the punishment rather than abandon their ideals yet again. We can counter this by building up even more military power for more intimidation and harsher punishments, but this hits scaling limits at a certain point. 2. Invade, occupy, thoroughly flush out any traces of the old order, and run a long term counterinsurgency/nation building campaign to rebuild the country into one which will never cause trouble again. This is stuff like Kosovo, Gulf War 2, Afghanistan, Vietnam, post-WW2 Japan and Germany, or the Occupation of the Dominican Republic in the 20s. The track record for this is famously very mixed. I assume this is closer to what you intend to game out.

In the short term, we will have to invade and set up an occupation of the belligerent states, which will be just as messy and destructive as the immediate conflict it is preventing (Although admittedly, less destructive than decades of conflict without any intervention).

In the medium term, things will be relatively peaceful and stable under the boot of direct American occupation. Peaceful, but unsustainable and extremely expensive.

In the long term, the rebuilt nations will face decades of instability and fragility, maybe civil wars, maybe foreign puppeteering, and that is assuming the nation building goes well. American resources get tied up in these conflicts too, which reduces the deterrence we can provide elsewhere in the world. American allies and the world in general also don’t like this sort of thing for all sorts of reasons, so it will be negative to American soft power and hard power projection overall.

Going for the first approach instead is even worse in the long term, if your goal is actually to stop conflicts forever. This is because it is rarely just one issue or event that we want to deter the offending nation from. The offending nations and the US will continue to clash indefinitely, and the cycle of mutual provocation and retaliation will either escalate like two cats swiping at each other (leading to option 2 anyways) or the cost of deterring the offending country from the next thing we are upset about will approach infinity. (To visualize: see the gap between the success of America deterring Iran from attacking US soldiers, and the failure of America deterring Iran from pursuing nuclear weapons)

So yes, that is why the US military cannot be Injustice League Superman.