Why Elgg 2
Elgg 2 matters because some long-lived communities are still leaving it behind.
The practical task is moving responsibly toward supported software without losing groups, profiles, files, and custom behavior.
Legacy LTS context
Elgg 2.3 was once the long-term-support branch, but it is now well outside support.
Community features
Older Elgg 2 communities may depend on blogs, files, groups, pages, message boards, likes, and custom plugins.
Upgrade pressure
Site owners need to review plugins, themes, PHP compatibility, and custom code before moving.
Staging and QA
Migration should be tested off-production so permissions, plugins, and user experience can be checked cleanly.