Diffusion of responsibility is thought that when other persons are present then single person will not be held accountable for doing (or not doing) something.
According to this logic other members are also responsible for omission or commission of the task and therefore answerability of every single person is very less.
Example- Diffusion of responsibility is why certain urban amenities are not delivered like water supply (Jal Board, Municipal body, Ministry of water).
It is based on the idea that “Everyone’s responsibility becomes no one’s responsibility.”