[ Thanks to AV for this link. ]
Maintain Old Releases
People are always resistant to change and switching your desktop
environment is a major change. When KDE and Gnome both had their
last major releases they promptly dropped their previous releases
like a bag of bricks. The Enlightenment 17 desktop, while still in
development, has been stable and ready for use for a long time now.Even so they have team members that maintain their older E16
release. It is still used (and liked) by many and there are no
plans to discontinue it any time soon.