I think there are a couple of reasons behind it. First, it stops rogue programs from running in the background, making the system more secure. Second, and IMO, a bigger reason, is ARM processors just don't have the horsepower of and i5 or i7, so suspending an app that you're not really using, makes sense there.

>With some more leaps like that we'll get something like DOS. It runs really fast on modern hardware.
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>>>What a giant leap forward.