Biggest Software Flops of All Time

Apple iTunes was a great success. Apple Music (imo) could join the ranks of "3. GNU Hurd (1990–Present)"

The article lists bad software that flopped. NeXT was mentioned that could be good that failed (or got subsumed). Lotus Improv is something that could be done today as a collaborative web app that I'd like to see. Is this Airtable?

Other flops (ultimately) Rich client platforms: Adobe AIR, MS Silverlight, JavaFX, Netbeans, Eclipse RCP, Dart/Flutter (in the making?).