Every single person at my large software company uses at least 2 displays + laptop, that's the standard setup. It's just objectively better for productivity to be able to look at multiple things at once without having to cram them into a single monitor.
Terminal, Slack, IDE, and browser each deserve their own monitor ideally. Personally, 2x vertical monitors side by side is a nice to have for programming so one can be for IDE and the other for reading docs/articles.