It could allow Microsoft to threaten to use trademark law against competitors who support the Excel file format.
It would also mean Microsoft would need to provide indefinite support for a function name that might not survive more than a few marketing cycles.
You're talking about a product which still to this day thinks it's an excellent idea to have formulas be translated, with no support for the English version in other languages. I switch my Excel to Norwegian and I have to use SUMMER not SUM, and opening any sheet with SUM will just fail to compute.
So yes, it's a terrible idea, but it's also an entirely normal Excel thing to do.
At work we have a lot of Excel sheets being sent from customers that are basically data dumps from databases. People export to CSV, open it in Excel (not import), and tada, very convenient. Except now those numerical article numbers are missing all the leading zeros, half the weights are dates and so on...
It sure is one enticing hammer...