This is what folding phones are great for. The extra space is great for multitasking, reading spreadsheets, viewing calendars, reading documents, etc.

They don't really help with writing or editing text, unless you have big hands and need a larger keyboard. Most of the difficulty with text editing are related to the cursor, as the article points out, and a bigger screen doesn't really help. I suppose the extra real estate can be used for a docked or floating menu.