It is then the same as Microsoft/Google or any other for profit company - you also get "software as is" and even if Excel blows up all your data MSFT is not liable for it. But still there is expectation that they will fix bugs that blow up someones data.
The thing is I pay for for Excel so I expect and demand them to fix their bugs! If I use an open source library for free I have no right to demand them anything, I can hope they will fix their bugs, I can contribute and fix the bugs myself if I can, but I have no right to the developers time or attention.