It's like a player who gets a clear shot on goal, no goalkeeper, and gives up on shooting because he's looking at the crowd.
The user who abandons checkout already wanted to buy. The decision was made. What broke was the path between intention and the confirm button.
The Problem
The checkout had too many fields, texts, and buttons scattered around. The user got lost in the flow itself not because he was stupid, but because the design wasn't guiding him.
It was functional in the sense that it worked. But it wasn't intentional. The information overload made him think when he should have simply acted.
