Seriously, how do bands do this?

I don't like the song, but that. Good song doesn't take crazy quality to be a good song.

i agree but 90% of the time it is way better to have a better mix.
There are tons of underground bands that i love because they offer interesting ideas, structures, atmospheres but with shit quality. Sometimes i don't care but it's hard to analyse and especially when you want to present a new band you've discovered to your friends or on the net, it doesn't go smoothly without a correct mix.