Ecleti has has revved Text Converter (http://www.ecleti.com/osx/totextconverter/) for the Mac to version 1.5.1. The app converts various file formats (PDF, HTML, RTF, RTFD) to standard plain text using drag and drop. Version 1.5.1 is a maintenance upgrade with performance tweaks and bug fixes. Text Converter requires macOS 10.10 or higher and costs $4.99.