We now manage a network of over 250,000 NAS devices that are part of our network. So we know how to handle devices going offline without losing data. This approach has been used at scale since 2014.
Best for archive and backup. You can also see how Vivint uses them to store video clips and stream them to customers when needed: https://crowdstorage.com/solutions/
Managing a distributed network has a much lower cost structure - no capital investment for hard drives, no electrical cost for running the hard drives, no cooling costs, etc.