Hello Steven.
I use a Surface Pro 4, which is a Microsoft-made device with none of the so-called 'embedded software' you mentioned. The recent 1809 update removed my documents as well- though I was fortunate enough to have a backup of it on a USB, which I restored after rolling back the update. Therefore, your argument is invalid.
Windows 10 is a mess in general, and definitely not the "most reliable windows EVER!!!!". Every day I slog through at least half a dozen problems regarding Office or OneDrive or other Microsoft products being unable to work properly on what is basically a vanilla Surface Pro 4. If that isn't a sign of instability I don't know what is.
There are issues with OneDrive (I'm not doubting that) but, I haven't encountered them, my 1809 system works perfectly without any problems. You must have had OneDrive synched when you did the update to 1809 and that is why you have problems but, that is a know cause of loss of files.