Spreadsheets are one way of consuming 2D _data_, which most business data is. They also provide a very easy interface for thinking about basic transformations on this data: the data is very visible, and every transformation you make is therefore very visible as well. Really: it means folks don't have to worry about control flow.
I agree with other commenters as to the effects of 2D code. I've spent the past year talking to 100s of Excel power users, and it's pretty clear: at any scale, spreadsheets get incredibly hard to follow, audit, and maintain.
The best of both worlds, IMO, is a spreadsheet for data visibility, and a program for transformation visibility. I'm a bit biased though, because this is exactly what we're building at Mito [1].
If you want to see more of our thoughts on the topics above - check out this blog [2] exploring the relationships between REPL environments, spreadsheets, and noteboooks!
[1] https://trymito.io/hn [2] https://trymito.io/blog/repl
claiming that it's the code's 2D-ness that makes it beneficial