True for the most part...sometimes is really more about apps pissing you off because they think you cant live without their unused processes clogging up the taskmanager(even when they havnt been launched)
A lill' bit of system-vanity, eh?
Plus,a clean taskmanager makes it easier to spot things that should not be there.Bad thingys.
Imo, unless you're a complete n00b you know what's good and what's not, in the taskmanager
But yes, in essence, the less you have to sift through the easier you spot the 'rotten apple(s)'.