"We will accept you, and make something useful out of you, no matter how worthless and terrible you are." So the military?

Once, perhaps, at least in some places.  Not so much here and now.  The military is too critical in its role to be a welfare program for the dispossessed, and also (like so many other things) too skill- and technology-intensive for actual bottom-of-the-barrel types to function well there even *after* they’ve been kicked into shape.  It is not an accident that there is no interest group more furiously opposed to the reinstatement of the draft, in America, than the American military itself.

Also, once again speaking as an American –

Our national culture, to the extent that we can still be said to have one, has “valorize the troops” as one of its key components.  This means that the American military is a pretty high-status institution overall, and losers will be outcompeted there, just as they’re outcompeted in all other high-status institutions.  It also means that everyone involved is going to resist diluting its brand with the introduction of human slime in large quantities.  It’s true that our “national culture” is disintegrating fast as social rifts widen, and that the moral status of the military has become controversial, but…“take the most bitter and volatile people we have, enlist them into a raging culture war against their fellow citizens, and give them guns” may not be the best plan I’ve ever heard.