it is correct that people suggest Home Sharing or iCloud, both have their pros and cons.
the reality is that iTunes cannot "sync" among computers / devices the way we natually perceive.
it is to do with Apple's control of copyright purchases, and i think Apple is still working out its Cloud strategy or feature (and in my opinion, it will never match the level of services Google can offer).
with HomeSharing, you can see the shared contents on another device, but there is no syncing and you have to copy manually. also, both devices have to be on the same WiFi network. i won't be able to see shared contents if I am using public WiFi in Starbucks with my MacBook while my iMac is at home on WiFi. but there seems to be a problem to access shared contents on iMac or MB (I am using Lion OSX on both), with devices using IOS6.
with iCloud, the catch is "Purchased" via iTunes Store for music and movies. if I got some music from internet or friend and add to iTunes on iMac, it won't sync to my iTunes on MB. it will only sync if I purchased music from iTunes ... or you pay to use iTunes Matches services which try to recognize your music library (i think the same applies and Apple will have a way to make sure it is a legal copy) and then push to download to your devices. of course, this does not apply to Pictures, but then you have to pay to use iCloud if you need storage beyond 5GB.
so it is a choice between sync (multiple copies but you can access offline because they are physically stored on your device) and share (one copy but you need internet connection (to the same network for HomeSharing).
I am sure all these are careful calculation and conscious design from Apple ...
and that's the tradeoff you have when you are tied to Apple ecosystem ...
i can see thw way some of these things work are already out of touch.
that is probably because Apple is mainly selling products (hardware and software), instead of services.
e.g. i don't need multiple copy of the same content, just because i have several devices.
ideally, we want one copy, and then able to access any type of content, anywhere, anytime, with any devices.
that's the way to go in my opinion, whether Apple is doing it or not.