In truth, the first couple statements make sense to me in isolation, but not in the context of our conversation. That might just be my brain with lack of sleep at the moment, though.
I don't know what the qualm is with not having all heroes to begin with, but it's preference since that's how I was introduced to MOBAs. Having to earn the currency to own a champion gives a small sense of accomplishment for me. On top of that, earned champions can have customized playstyles with runes and masteries. Males for shitloads of fun when I can play a champ I love in 3 different roles viably. On the other hand, I've read the lack of runes/masteries make DOTA a bit more skill-based competition.