For home users, maybe true. Though I'd imagine many home users of Excel would be better served by Google Docs.
But it's a massive number of business users. Everyone at my company relies on at least one spreadsheet that has macros or complex pivot tables. It's a bit scary how much critical data is moving through Excel in the typical business. My understanding is that Wall Street relies pretty much runs on Excel.
Speed, too. You run into some pretty hairy Excel constructs, and the Excel team's optimizations really pay off.
It's been a number of years, but I used to spend a good part of my days in Excel. It has its own quirks -- may its inaccessible underlying formatting constructs be damned [1] -- but hey, can that sucker eat spaghetti (code -- so to speak).
(BTW, it may help to understand that many financial constructions are politically driven and otherwise idiosyncratic, to the point where you will never be able to code them up in a formal, regularized, and consistent construct. The "pointy haired boss" (whichever one, on whatever day) is always having you either insert or compensate for another "x factor".)
[1] As one, but not the only, example, try formatting 999D9 as text with leading zeros, some time. You'll find an odd result you eventually realize is the value with D9 expanded as an exponent. Like Fortran (so I was eventually told while mentioning this behavior -- never used the language, myself), Excel treats not just "E" but also "D" as demarcating an exponent. (Besides, you're formatting as "text", so why is it interpreting the end as an exponent? Although I can see where the leading zeros specification may throw it into a different mode.)
The customers for Excel are accounting firms buying 50,000 seats at a time. And the CFO probably uses it personally, so it needs to keep him happy. In contrast to most "enterprise" software, which is so bad because the people making the purchasing decision never have to actually use it themselves, they just get their PA to do it.
Managers love Excel. Some of them are really good with it. It's probably the wrong tool for their job, but it is a tool they know how to use. For managers it's the lingua franca of data manipulation. They view it the same way most of us view pipes and the Unix command line tools.
If you'd stopped at "Managers love Excel", I'd agree with you. Unlike the lucky duck up above, I've never seen a manager write a spreadsheet that included a single macro, active cell or calculation.
I've only seen managers use Excel to format columnar data, and then only because "Word" does such heinous things with text in the cells.
But it's a massive number of business users. Everyone at my company relies on at least one spreadsheet that has macros or complex pivot tables. It's a bit scary how much critical data is moving through Excel in the typical business. My understanding is that Wall Street relies pretty much runs on Excel.