@publicvoit part of the lock-in effect for Obsidian is their live preview mode -- instead of seeing the underlying Markdown text, you see that text rendered in a way that is particular to Obsidian. When you combine Obsidian's unique extensions to Markdown (like callouts), along with themes and custom stylesheets, you're no longer working with just Markdown but Markdown as rendered by Obsidian...and then you're totally locked in despite the supposedly open file format.