Context: I am an employee in a semi-small company, where most people have multiple responsibilities and tasks concurrently. Most of the time, there is no explicit/formal definition of projects responsibility. There is a hierarchy with about 5 managers managing about 5 employees each. Work contracts usually last for ~5 years, so there is a relatively high turnout rate, including for managers (this is because of the company's field, not because of the company ambiance).
Issue: Since project responsibility is rarely assigned explicitly, it has become customary for managers and team members alike to assign it implicitly to anyone who either:
- propose an idea to approach the issue, even partially,
- or is assigned a smaller task related to the project (eg, an intern or team member is asked if he/she can complete a small task related to a project, and from there the project responsibility is assumed to be on his/her shoulders).
I feel this attitude is counter-productive, as it prevents team members to voice ideas or invest in projects or tasks even partially, as doing so would usually result in them getting responsible for yet another project.
Question: Is this kind of implicit delegation of project responsibility common and normal? If not, how to avoid being the target of this method without being rude or unprofessional?
/EDIT: Thank you all very much for your answers, even though I cannot apply most advices because of other issues at my company, this made me realize the complexity of the issues I am dealing with, with our corporate culture being one of the culprit. I divided the accepted answer reward and the bounty to two answers as I could not accept both.