“OWA Light was an important compatibility experience when the web needed it. Today, the full Outlook on the web experience is the right place for us to focus.”
OWA Light was the version that loaded on a bad connection and worked with a screen reader. Now everyone gets the full JavaScript client that assumes a fast laptop and a modern browser. The people who lose are the ones on slow links, old hardware, and locked-down kiosks. Microsoft calls dropping the lean option the “right place to focus,” which is corporate for we do not want to maintain the version that respects your bandwidth.