I suppose. But as a software developer I've never created an Excel spreadsheet that wasn't first a CSV. I do most of my own work with local data files in jq for JSON or q for CSV, then go from a CSV to an Excel spreadsheet only when it's time to communicate that data with non-programmers.

Their niche is clearly supposed to be in helping developers and data scientists make that same leap, from the tools and formats native to their data pipelines to feature-rich spreadsheets as an export/reporting/analysis format for consumption by people who otherwise don't code. CS V support (especially for huge files) is unusually important there.