EDIT: I don't care for MSFT, I loathe Word. But Excel on Windows is a genuinely fine tool -- overused by a lot of people b/c the Windows anti-pattern keeps them from proper tools, but still a really useful piece of work. You can't do detailed modern financial analysis without it. The alternatives -- Linux, Google Docs, even Excel on Mac -- aren't even close.
What some courses teach is not financial math - it's "how to get numbers out of a 12C". This is just perverse.
They don't need Office. They are just used to it, much like accountants are used to their 12C's
Now most students are being trained to use Office at school.
I use to see the world from an "Open Source" programmer's point of view: "You have the choice to use OpenOffice". But then after I saw the reality for a while, things start to sink in and it becomes obvious that people don't want to be liberated the way I thought they ought to be.
People are OK with MS Office. It becomes a piece of software that, no matter how hard geeks want to argue about the Pareto Principle or not, will stood the test because people were being trained regardless its complexity.
So yeah, from "feature/functionality" perspective, there are alternative. But from skill-wise, willing-to-learn aspect, there aren't until Universities and/or schools start teaching young people to use something else.
OTOH another argument is: you don't need the other alternatives if you have Office.
A person close to me is currently taking Accounting courses and calculator + paper do not cut it. You need Excel.
There is little stopping them from using newer tools but inertia.