Pretty sure Excel is the largest coding group in the world, they just don't share their code in Github.
When's the last time you got a prize for programming outside of your paycheck or a signing bonus? Communities definitely have shared events and what better shared event than a competition?
As for programming prizes, "last week" if we're counting bug-bounties, "a few years ago" if we're counting CTFs, and 5 years ago if we're not.
Clearly there is an Excel community in the general sense but as far as I know it isn't centered around any particular venue - at least, not one at the scale of GitHub or Scratch
Like magic, fluid, self-associative communities.
Of course, this would probably require sharing internal corporate data which is a big no-no.
https://www.microsoft.com/en-us/microsoft-365/blog/2023/03/2...