Comment by heavyset_go

Clients are going to send you Office documents, spreadsheets, etc.

Maybe you'll luck out and get something cross-platform or online, but 90% of the time if a client is sending a document, it's going to be something from Office (or rarely, Pages).

Spreadsheets can run scripts, and important ones you need to be able to run accurately, and not just hope your alternative office suite works.

I hate it, but it is what it is.