You're right in regards to everything you've mentioned but it doesn't disregard that a Linux based system is vunerable also. They are not as vunerable as windows but in the same retrospect it is vunerable. Because I am 100% sure that Google, The NSA and Most banks who are running Linux are running some kind of AV software. You don't know if you're going to get in an accident but you buckle up for your safety when you get into your car just in case, because it could happen and cars has crashed before.