You need plants to make oxygen though. You might not have to think about it, but you need it and someone has to keep making it.
 
Unless very small, there really is no such thing as a company without a full time IT staff. You can outsource the stuff, but again, unless small, generally that is more expensive in the end than an actual IT staff that is full time.
 
Think about your stuff at home, I'd wager you've had IT problems of some sort at some time. Could be as simple as the internet not working and you call your ISP. It could be a computer dies, or you lose some files from a crash and try to recover them, etc., etc. Maybe you do it yourself, or maybe you have a family member or friend who helps you, or maybe you call your ISP and/or local computer repair shop every single time.
 
Now take that and multiply it by the number of employees you have, plus a large extra fudge factor for whatever extra shared and networking resources you have. Pretty quickly you are at "needing a person handling this stuff full time who knows what they are doing".
 
In my limited SOHO and SMB experience, the HO part can generally be up to the end user with a tiny bit of knowledge. The SO part can often be an employee who "knows this stuff" as part of their job and/or contract it out to a company the specializes in the small office IT support. Once you get to SMB, where you start talking more medium business (and by this I mean generally once you are talking offices over about 20 employees), you REALLY need a full time IT person. Ideally a small team, especially once numbers start getting up there on the business size.
 
20 employee business might be able to handle contracting it out still, barely. A 50 person business probably can't. A 100 person business DEFFINITELY can't.
 
PS When I speak of business size, I am generally talking about "white collar"/people using computers/computing devices for most of their work. I don't mean, for example, a resteraunt which might have 40 employees, but 2-3 POS machines, maybe a couple of kitchen order trackking machines and maybe the manager has a computer in their office in the back and that is it.
 
Downtime, document loss COSTS!