User blog comment:MisterWoodhouse/Social Activity, the 2010 Editor, and Unpausing Migrations/@comment-37371166-20200922174318/@comment-26339491-20200922223321

Discussions has had the restriction on editing one's own post for regular users since its very first release years ago. This is not a recent change. And since comments and message walls are built on the same technology, they have that same restriction.