CSV isn't supported in Excel because Microsoft prefers it. MS prefers its own Excel format. Excel supports CSV because a large enough majority of Excel users wa

CSV isn't supported in Excel because Microsoft prefers it. MS prefers its own Excel format. Excel supports CSV because a large enough majority of Excel users want it, which means MS includes support for it. For MS to remove CSV support in favor of Arrow or Parquet support would not benefit MS at all, and would make many of its customers push back, so I don't see it happening.