I mean there are good arguments both for and against compulsory military service
Are there good arguments for it? If it’s compulsory, maybe you need to run your country differently so people feel its worth voluntarily defending. And/Or you can recruit heavily in areas where folks are disadvantaged and have few options, dangling education in front of them in exchange for being willing to kill or die for you.
The funny thing about knowing 18 year olds at 50+ vs being 18 years old is you can see the children these kids still are. Allowing them to join? OK. Forcing them to murder for you? As a veteran who joined at 19, no.