Err...
Assuming that we're always going to be stuck with closed source commercial software and sorry to keep banging on about Storage but that's mainly what I do at the moment - I've yet to see a FOSS backup system which is worth more than a cursory look. The new platform will require commercial companies to compile their software for ARM.
I am an ARM fan and I am a linux fan, I'm just being realistic here - the killer commercial app (whatever it is for whichever company) already works on Intel, to get a foot in the door ARM servers will have to have whichever app that it - it varies for each company - compiled on ARM.
Bonus answer:
Because not everyone only runs one or two linux boxes that they're happy to gaffer'n'string together with homebrew scripts. Many companies run thousands of mixed OS machines across multiple sites and require central management consoles, access to all the facillities of really big storage systems, encryption, key management, media tacking, media ageing, etc. etc. etc. You just can't do this with a few scripts and cron.
The vast majority of big companies won't even use cron because it's so hard to manage on more than a couple of machines. Just think of the hassle involved if you want to stop your 10pm backups if there is a thousand machines each kicked off by CRON?