Oh, I discovered this alright. To do this using OS X and Android I have to do this terribly hard process called "drag and drop". Once done I can even delete the data from the Mac if I don't want to be duplicating that 100GB of data on both my Mac and phone.
I thought you said the cloud does everything? Changing your story?

Drag and drop doesn't even back everything up. Cloud doesn't back everything up. Even if you did both you'd still lose data if you wiped. Try again.
It's not synchronisation software though is it? No, it isn't. I can't remember the last time I plugged my phone into my computer anyways.
Even then I dont need to plug it in:
http://www.airdroid.com/
You seem to be easily confused by words. Nobody said anything about sync software, iTunes, etc. All I said was sync. You do know what sync means, right boy? There are even different kinds of syncs. Partial sync, manual sync, full sync, automatic sync...
Once a week I back up my iPad to my Mac. I've been around long enough to know it's not if but when you'll need to restore from a backup. You're putting a lot of faith into something you don't have full control over. Good luck with that.
I've never understood why people would want media blindly synchronised from a device with very large amounts of storage, to a device with relatively small amounts of storage without any input.
I never understood it either, which is why I don't do that and why I manually choose what movies and music to put on my iPad. Assume much?
I don't know, I don't keep movies on my iPad - I almost always stream them - either from cloud storage or from my home server.
There you go not reading/comprehending again. Missed the part about not having unlimited data, did you? I don't watch movies on my iPad while at home. Why would I do that when I have a home theater? So I either stream movies/music away from home/wifi and consume my entire data allocation in a matter of hours or days or I make use of the device storage which I paid for for a reason. I still have tens of gigs of space free on my iPad, why wouldn't I make use of it? Does it do me any good just sitting there unused? No.
I can't remember the last time
I absolutely had to access 100GB of data at ONE time whilst being away from home/wifi.
Even if I did, 100GB with Google Drive costs $4.99/mo.
https://support.google.com/drive/answer/2375123?hl=en
Who said I had to access all of it at one time? There you go making wild assumptions again. You're good at that, must have a lot of practice. Oh, and more lack of reading/comprehension again. What good is 100GB of Google Drive space if I'm out of data on my data plan?
I travel a bit utilizing various modes of transportation, whipping out a 15" rMBP? Yeah...not exactly convenient or practical. No wifi or cell data? *whew* Glad I don't have everything stored on the cloud where I can't access it.
I'm glad your setup works for you. You may not fully understand the consequences of not having proper backups, but that's a mistake most people only make once.
No part of my setup is a compromise or inconvenient for me and I know for a fact that I can fully recover ANY of my devices in a timely manner and without data loss (Within reason, obviously there is going to be data loss if there's only data in one location that doesn't exist anywhere else).