Recently I've been pondering collective vs. individual ownership and commitment, the theories behind it, and how to respond to someone who many not have considered why collective ownership and commitment is important. If you are involved on a team that is assigning responsibility to individuals, you could respond in several ways. My own impulse may be to respond either with frustration or to smile, nod and wink to my more agile-aligned team members. However, I have never found these types of responses to be very productive ;). You could also respond by informing the team that the agile community is full of luminaries who tell us that individual responsibility is not compatible with good results over the long term. However, as you can imagine, it also won't be an effective strategy just to tell your team that Johanna, Brian, Bob, Esther, James, Jeff, Mary, (etc) and you don't think this is an effective way to manage the work. Instead, I suggest that you a attempt a face to face discussion on the pros and cons of assigning the work to the team vs. the individual. Here are a few things you might use in your discussion.
Team ownership reduces the risk of having or creating one 'smart person in the room' (i.e. bottleneck) who does all the work. Even though Jim may be the best person to complete the job, if Tim and Jane work on it together with Jim it will take a little longer initially to complete the task, but those gains will be realized over the long term as the whole team becomes better at accomplishing each task and filling each role. While a cross functional team isn't always easily or immediately created, eventually that team can function effectively to complete any task even if one or more team members are missing.
Collective ownership should result in less items that are in progress. Work in progress tasks have zero realized value to the organization's goals. If we commit to and own items as a team, we should work hard to get them done one at a time so that we can realize the value of those items sooner. Rather than 5 people completing 5 tasks individually that are finished together at the end of the month, task 1 is finished and creating value at the end of week 1, task 2 at the end of week 2, etc.
Quality has a better chance of being built in from the beginning when a team owns and takes responsibility of a task together. As the team works together on a backlog item, we will collectively discover our 'quality blind spots' earlier in the process and adjust accordingly. When I work on an item myself and then present it to the team for review after I'm finished, there will be more re-work required to incorporate the ideas of my team members in order to mark the item as done. It is critical to get feedback early and often in order to 'fail fast' and improve quality. Teamwork is an effective way to accomplish this.
Finally, collective team ownership promotes... teamwork. Individual accountability and responsibility tend to generate selfish behaviour (I'm working on my task that I'll be measured on so I can't help you with yours). Team accountability and responsibility builds a stronger team because if any one task is sub par it reflects on the whole team and not on an individual.
Of course, this doesn't work very well if we don't sit together - which is why we do.