Re: Please explain to me ...
Office365 sits on Microsoft's Azure data centers. Your services and data are locally and geographically replicated. Not only that if your tenant is having a problem it may only affect a small portion of your users. User accounts shift from server to server and not everyone will ever be on the same server. So if one person is having a issue the person next to them might be fine because they are on a different server. What does that mean though? Your subscription pays for the hardware, licenses and the MICROSOFT engineers to maintain it. What does that mean to you? It means not having to replace hardware your exchange sits on.. ever... Security including SSL (encryption) certificates, firewalls, disk encryption, spam/virus/malware filters w/ their Machine Learning algorithms, maintained by Microsoft. Service Level Agreement (SLA) is the peace of mind that is financially backed by a 99.99% up time 24x7x365. Support: unlimited customer support for all Microsoft products that touch Office365. Software subscribed through Office365 is always updated to the latest version. no more licensing headaches or software assurance gambles.
Connections between the Azure data centers are dedicated internal infrastructure. Meaning Microsoft has ran their own fiber network between each data center. They actually own submarines for getting across the oceans.
Microsoft currently has 34 data centers world wide (https://azure.microsoft.com/en-us/regions/) 6 of which are in the UK, Eur, Ger regions and 2 more going up in France.
The comment "How much does it cost to not be able to do anything for a half day or MORE?" You cant think of anything you would rather be doing? The cost of babysitting a simple backup is too great no matter the number. Humans time on this earth is finite and spending a half day for a back up that is not going to matter in 6 months to a year is never a good use of time. Backups should always be automated no matter the solution.
This article could be considered click bait to an IT admin. You do not have 100's of thousands of servers running without having problems at any given point of time. Microsoft is not perfect but they do all they can to mitigate any issue from impacting the customer. because they are not perfect this is also why they ask for .01% of downtime which equates to 45 minutes out of the 43,800 in a month. 45 minutes of downtime is still considerably less then spending half your day doing a backup.
I do not work for Microsoft but I have worked for some of their gold partners for the last 3 years supporting Office 365 and Azure services.
Here is a article that lets you know your data is handled in Office365: https://techcommunity.microsoft.com/t5/Office-365-Blog/What-Happens-to-My-Data-in-Office-365/ba-p/84059
I hope this answers some of your questions.