As Project Managers our aim is to gain respect from those around us as we guide a project team and ultimately a business to deliver results from its investments in projects. This can only be achieved by holding everyone accountable to their piece of the project puzzle.
There is an art to Project Management and sometimes non more so than having people held accountable to do their part on a project. This can be made even harder with an organization in the midst of change (as we all seem to be in todays business world). The art comes from the delivery of the message when someone is not pulling their weight on a project and needs encouragement to ensure they complete what they are accountable for. There will be occasions when they do not complete what is assigned and there poses the project manager with a problem to solve.
Letting them slip and impacting other parts of the project ensures that the PM has not done their job. Holding them accountable and escalating the problem could (and i say could) impact their work on the project. But it is the job of the PM to have those conversations and work with team members to ensure they know what is expected of them and once in a while call them out. It needs to be done with respect and at the right time.
It is never easy but everyone on the project team and in the organization as a whole must understand it is part of the job and support them in doing it.