

Well, the purpose is to be denied by the foreign country. Or, to be accepted by it, depending on your perspective.
Typically your own country doesn’t (shouldn’t) care of shit about your passport, because according to the declaration of human rights, you are allowed to come and go to/from your country as you please. But other countries don’t have to give you that privilege.
(I do think they should have to, though!)










USA is only waging wars of aggression. It would be horrible forcing people to that shit, IMO.
In Finland or Germany it’s very different because our armies exist strictly for self defence. When the US military should see military action, is decided in D.C.
But when the Finnish military should see military is decided in Moscow.
If your wars are something you fan decide about, it would be extremely immoral having compulsory military service.
In countries that cannot decide when to not have a war, it’s immoral to not have compulsory military service, as that would mean only the poorest having to bear the brunt of the war.