It is based on markdown files and you can link them by writing "[[my new note]]". It also supports tags etc, all text-based.

What is the purpose of the "dragging notes" flow you mention? I am sure it can be done in the text-first way that Obsidian uses.

Late to the party, but there's a "canvas mode" in Obsidian where you can sort of group notes together and drag them around. Other than that, it's also got a graph view, so provided you tag and link notes properly, it will show you related notes in the graph.