One-time purchase software would become dramatically more sustainable if platform churn could be ground to a halt. Most types of software achieved peak usability and functionality somewhere between 5 and 25 years ago and there wouldn't be much reason for anybody to upgrade if their one-time purchases continued to work in perpetuity. A substantial number even
prefer e.g. Word 2000 or Photoshop CS1 over their modern incarnations but can't use those for either technical or legal reasons.
Instead, the reverse has happened and platform churn has risen to new highs, necessitating subscriptions.
