The other team members were capable, but early on they chose to defer to Harold.
Harold decided to play a greater role because the others seemed passive and he wanted to move things along.
As Harold did more, the others grew used to it. Some resented it, feeling that Harold was treating them like second-class citizens. A few secretly hoped that Harold would fail so they adopted a passive-aggressive approach: If he directly asked for help, they've give it, but they wouldn't volunteer assistance and any contributions that they gave would be minimal.
Time passed and Harold started to feel overwhelmed. The work piled up, the others didn't pitch in, and Harold harbored a slow anger toward the rest of the team.
The others in turn blamed Harold. "We would have helped," they muttered to one another, "if only he had permitted us to participate."
"Gloryhound!" they charged.
"Slugs!" fumed Harold.
Each side thought it had behaved properly and the other was at fault.
The only amusing part of the tale is they all thought their story was unusual.