Without commitment, not much is achieved. Lack of understanding of commitment is the reason why many Agile teams in the world are not as effective as they could be. They take in much more work than they can finish resulting in not finishing their work on time. Anti patterns set in that are difficult to change, team members question efficacy of Scrum. There is no data that supports effectiveness in the team due to lack of proper velocity, predictability, etc. The burndowns look messy, and all the paraphernalia of struggling teams show up.
Commitment brings a force, it brings power. Just like when a river is committed to the two banks, it has a force, you can generate electricity through it. In the same way when a team is committed to a certain way of working, of delivering their work on time, it empowers the team and makes them a force in the value delivery flow. It helps the team be healthier, happier, more successful. Such teams are a delight to behold and they take pride in their work.