As a project manager you should know that you cannot make every decision that presents itself during the course of your project. You may know or anticipate that there will be conflicting views amongst your stakeholders concerning approach, priorities or any number of things. In actual fact there are all sorts of reasons why the project manager needs help from the senior managers and directors of your company.
I am tempted to say “all” , but I will play safe and say “most” project management methodologies mandate that a project must have a “Steering Group” – you may call them other things like “Committee”, “Project Board” or whatever. The overriding purpose of this group is to unite the various interested parties in the common aims of the project and to enable effective project governance and decision making.