As an example, Adobe Acrobat. It's obvious why it needs 3 services, a persistent update checker, a couple shell extensions, 2 non services set to run at startup, and always running extensions for Outlook, Excel, and Word. All totally necessary things that a restrictive app model would unjustly break.
Don't forget it can randomly decide to try and render your computer inoperable because it guesses you might've had a dodgy version of Photoshop installed at some point in recorded history!
