Yes, we'd all prefer peace and leaving each other alone, but if some other nation comes to kill your countrymen and replace your democracy with a puppet, suddenly just relying on pacifist ideals doesn't work well anymore.
Most of the time, these commenters don't want to engage with reality as it currently exists. If you ask them what exactly you're supposed to do without a war machine if some other guy invades, they just have the silliest deflections and hand waving. Ultimately, they just want to say "war bad" from atop their high horse, as if other people didn't believe that war was, in fact, bad.
Ukraine is an obvious example. Ukraine wasn't doing anything to Russia other than choosing to gradually move culturally towards the West, which is their right. Before the big invasion in 2022, there were repeated attempts by Ukraine or by Western countries to try and forestall Russia's invasion by opening up negotiations and talking things out, and Putin didn't give a shit.
Diplomacy didn't work there. What would've worked? Having a stronger military, or even better, being allied with other strong militaries. Putin doesn't invade the Baltics for a reason.