One does still need to kill apps in iOS7.
Easily seen when new app won't login or parse data until you start closing others, right there in the multitasking window.
That's a tough path you're headed down. I agree with you but there are very persistent folks here that read how it's supposed to work won't see it any other way.
I've read the documentation, understand it the best I can, and then see in real life that a low memory condition causes issues. When my daughter has 50 applications in the recently used app list the lag going into Settings drives me nuts. Remove all apps from the recently used apps list and problem solved.
Blame Apple for poor implementation, blame the developers for apps that don't follow the rules, blame the full moon... I clear my recently used apps list every night. My phone doesn't have performance issues and games don't crash when I launch them.
I don't mean to sound snippy. Just left-over frustration.