I understood why #Trello feels so useless! It pretends that things are linear while they're not.
I looked through the cards in my personal Trello board, "Tinker's Tote", and I realised that they form a directed graph with loops.
It's insane to render it into columns by default! It creates a huge cognitive strain to maintain the graph structure in my mind.
That's another part of my life I'll be switching to #MarginNote.