The upshot though is: Think of battle at the time as being a little bit like some sort of bizarre college sport where everyone lines up, locked arms, and then smashes into each other. With, yes, weapons, but fatality rates were not enormous.
Spartiates - the tiny warrior elite of Sparta - are a bunch of very rich asshole frat boy jocks who are far too cool to train or anything, but that was fine because training doesn't really matter for a glorified shoving match, and nobody else was bothering to train either. What matters a bit more is that they spend every day living together, eating lots of meat, getting drunk, raping and torturing slaves, and if they feel like it, going hunting, so they're all beefy, well fed, fit, and can afford the very best gear. Also they have excellent cohesion thanks to all that bonding while drinking and/or torturing slaves, so man for man, they're pretty effective. Of course, these battles/shoving matches are big enough that they have to drag along a bunch of non-citizens and slaves and allies from other Greek city states to pad out the numbers, so that undercuts their advantage. Although note that Spartiates are by far the most prestigious, and there's a strict rule that both teams line up with the most prestigious on the right side, facing the enemies left side (where the weakest, poorest, and least prestigious units are slotted in).
So yes, individually, Spartiates were...well, not great warriors, but man for man they were the most effective fighters on the field, especially since they consistently faced the weakest opponents. But Spartan armies were not unusually effective, and Sparta as a polity failed to achieve its strategic objectives. History is full of glorious defeats where Spartiates lost impressively; so much so that in one famous instance where a bunch of Spartiates were captured by Athenians, they had to confirm that they were actually Spartans - not because they lost (that wasn't unexpected) but because they were expecting a doomed fight to the end.
So yes, Sparta was let down by truly horrible logistics and diplomacy, but their military record wasn't much better. Quite good at beating up their slaves and/or the weakest unit on the opposing army though, so there's that?