Quoting Wikipedia to Explain Why You Should Not Use Microsoft Office 365.
Microsoft 365, or Office 365 has a terrible record on security, which is one of the reasons you should not use it.
Another reason is that if your “subscription” expires, even the desktop versions will go into “read-only” mode and prevent you from editing or creating any new documents until you’re paying Microsoft for a subscription again.
Even the older licensing model required a “Product Activation” server, but it was only to check if you paid the licensing fee, one time, whereas the licensing fees for Microsoft 365 never stop unless you want the programs to turn into document viewers that can’t do anything else.
Let’s just look at what Wikipedia says about “Security” and directly quote it (note that this is the September 7th, 2023 edit, and it may change later. Microsoft even pays PR firms to vandalize Wikipedia and downplay and edit out embarrassing information.
In spite of claiming to comply with European data protection standards, and in spite of existing Safe Harbor agreements, Microsoft has admitted that it will not refrain from handing over data stored on its European servers to US authorities under the Patriot Act.[88]
In Finland, FICORA has warned Office 365 users of phishing incidents and break-ins that have caused losses of millions of euros.[89][90]
In July 2019, the German state of Hesse outlawed the use of Office 365 in educational institutions, citing privacy risks.[92]
In December 2020, the US Department of Commerce was breached via Office 365. The attackers were able to access staff emails for several months.[93][94]
–Wikipedia
So, Microsoft will turn over your documents to US authorities under a rubber-stamp procedure under the USA PATRIOT ACT, no matter where it claims to store them, and in violation of your own country’s privacy laws. Many of these procedures don’t even require the government to ask a judge in an American court. They can just get the files.
(National Security Letters work this way, and they couldn’t tell you they handed the files over even if they wanted to, because they come with a gag order. The point of this is you won’t know there’s an investigation until they’ve arrested you and have already built the case.)
Microsoft “online services” are notorious for break-ins, so Finland’s warning shouldn’t be a surprise. When they break into the server, criminals can take your documents and files too. They can use them to steal trade secrets or blackmail you.
The United States government has been breached at least once, and for several months, and there’s no telling where the Department of Commerce’s mail ended up
(Russians? Chinese? Even the US government gets no security when they use Microsoft products.)
Microsoft 365 is banned for use in classrooms in at least one German state, which has deemed it too insecure to even use at all.
Also, this is the stuff that survived Microsoft’s PR firm “pruning” things from Wikipedia.
None of this things can happen to you if you use LibreOffice, and store your documents on your own computer.
Also, LibreOffice never goes into “read-only” mode if you stop paying a monthly fee. There is no fee.
People working with/for online trolling firms (like IBM, who now promotes MS Office to Linux users via a Web browser) or who have been brainwashed by them like to paint people who insist on real software as some sort of aging hipster or a crank, but it’s all part of the rub.
“Web Apps” that do something that you could do with locally executed computer software almost always have few or no real advantages for you, but they do give someone power to steal and leak your data, and force you to constantly pay them more money under threat of losing access to the program entirely.
When I was a teenager, I railed against “Product Activators” for locally installed software too. I see that a lot of software uses those now, but I decline to use anything that makes you submit to a Web server to continue executing the program.
There may be some sort of “illegal crack”, which is what paying customers would always eventually have to do to keep their binaries working when the activation server no longer exists. So you can pay and THEN still be forced to make the decision between committing a crime or not, later on, after you use and need the software.
So far, Microsoft has hidden this facet by keeping the activation servers for, I think, even Windows and Office XP running, but they won’t do that forever.
(I do not support piracy of Microsoft software. Piracy of Microsoft software is always a terrible thing, and should never be done, because then there are more copies of the software. Also, they can come with viruses, but the Microsoft software itself is usually at least as bad as the virus that comes with it.)
If I can still use WordStar in DOS, why can’t a person who bought Office XP have binaries that will always work if they want to use them in 2050 somehow?
One point of subscription models is forcing users to update even when the program changes in ways that make it difficult for them to adjust to, or remove features they needed.
So add all of this to the list of reasons not to use Microsoft 365 or any “Clown Office”. ⬆