RTF is a rarity these days since basically every phone, tablet, and other handheld device can handle either PDFs or HTML (and ePub is basically just a ZIP file with HTML in a specific naming scheme and structure). Back in the day though you’d find RTFs more often for use in budget/jury-rigged eReader options. It’s much easier to parse, if nothing else.
RTF is a rarity these days since basically every phone, tablet, and other handheld device can handle either PDFs or HTML (and ePub is basically just a ZIP file with HTML in a specific naming scheme and structure). Back in the day though you’d find RTFs more often for use in budget/jury-rigged eReader options. It’s much easier to parse, if nothing else.