Does it matter? Background running processes should not impact the performance.
Of course background processes can impact performance. Computers are not magic. If you have an Android widget that someone sets to update every few minutes, then there will be an impact. If you run a background file download on iOS, it can slow you down. This is not bad; it's by design and usually done by user choice.
Heck, there are times on the iPhone where a nav program, VoIP program or even Apple's mail app have gotten stuck running in the background. It happens. I've had it happen with app updates.
And what's that about "when you need a task manager, you failed"?
Quoting Steve Jobs is like quoting a car salesman: usually meaningless. For it to be truthful, that saying should've been, "If people KNOW they're using a task manager, you've failed". (WebOS did this best.)
iOS has a task manager to kill wayward apps... that's what the X's are for in the recently used apps bar. It needs that task manager because Apple had to give up its original Home-button-kills-the-running-app paradigm in order to allow multitasking at all.