Having started in IT during the days when crashes and hardware failures were pretty well a daily occurrence, I’ve seen and participated in some disasters in my time. I even wrote basic disk testing and data recovery software in my youf. So I’ve always been meticulous about my own and my families backups.
After retiring I dumped the Microsoft rubbish and moved to Apple which has a feature that backs up incrementally every hour to an external drive, and a recovery program that allows you to recover generations of files and folders. Very handy, but I still do full disk backups on a regular basis on a grandfather, father, son basis. I use a 20TB drive running as a 10TB RAID for this. If the house went up in flames all I need to grab is the RAID 
I also have my stuff in the cloud, iCloud and, until last week, OneDrive. My wife’s away so to keep myself amused I thought I’d rationalise my data storage strategy, which would involve days in the study 
I want to share all my data across all my devices, desktop, documents, photos, home movies etc. etc. terabytes of stuff. I can then give access through file sharing to my wife and daughter. I do a lot of that already but it evolved overtime through a mixture of OneDrive and iCloud and it’s a bit of a pain to administer. I decided I’d dump OneDrive as I don’t like its design, and to consolidate into iCloud.
However, being the paranoid I am, I wanted to download everything on OneDrive, about 800 gigabytes, to make sure I hadn’t stuck something up there that wasn’t on one of my machines, in my Apple backups or on my RAID.
It was a nightmare. I assumed that I could initate a download for the whole shebang and just let it run away, but no. There were inexplicable network timeouts and inexplicable zip expansion failures. I spent, I suppose, three days downloading everything in bite (no pun intended) sized chunks. I finished last night and now I’ll start deduping and making sure everything is in iCloud and on my physical backups.
So this very longwinded tale is to basically say that OneDrive (and indeed iCloud) are really only file sharing and disk space saving services - they are not suitable for backups of critical data. There are dedicated Cloud based backup services, and I might look at those in due course, but unless one is using one of those (and even then perhaps) there is no substitute for multiple local physical backups.
