In software development, as in many professions, way up near the top of the importance list is getting things done. That's why defining the problem you're solving is so important. How do you know if you're done if you don't know what problem you're solving.
And knowing who's responsible for getting things done is just as important as knowing what done is. This is more than having a task list with names attached to each item, although that's critical too. Because solving a problem is more than completing a list of tasks. Especially now, with agile development and shorter design/planning cycles. Many design docs specify the verbs/functions that will be supported, but not the exact parameters, and that's good. It's good because at design time you almost certainly don't know the implementation details well enough to specify what those parameters will be.
Which leads to the issue. How can multiple people collaborate on building a thing, each with enough ownership and responsibility for their own parts to be able to make their own decisions, get the bigger thing to done? Many moons ago in an MBA class the instructor told us that our job was going to be less about the architecture diagram itself, and more about the white space between all the boxes in it.
And that's where ownership and scope comes into play. Diffusion of responsibility is a real thing. One way to keep your cognitive load down is to know what you're responsible for and not worry about the rest. And task lists with names on them are very clear. It's easy to say "I'm responsible for these specific things" and not worry about the rest.
It's also problematic. Because your customers want solutions to problems, not features. Each of those tasks in the list, by itself, is a feature. They need to be integrated with each other and the existing systems to form a solution.
Back in the early VirtualEarth days we had a very manual process to turn stereo image pairs into 2.5D extruded models. We needed to get our production rate up, so we were automating everything we could. Each bit of automation made sense, but they weren't exactly integrated with each other. After a few months of everyone throwing together tools and scripts the manager of our production team came to me and told me that we could go on unleashing all the tools against them we wanted, but until we got our act together and figured out a way to solve his problems his team was just going to ignore us.
That was a bit of an eye-opener, but he was right. We had taken the list of pain points, split them up into bite sized chunks and built tooling for a bunch of them. But we lost sight of the actual problem we were solving. No one was specifically responsible for making production faster/easier, so we hadn't done that.
So I took his feedback, took a step back, and looked at his team's problems. All it took was a little bit of workflow framework, better error reporting/management, and some written SOPs (on top of all the tools/scripts we had built) and suddenly we made significant improvements to the production throughput and acceptance rate.
Whether it's the PM, the EM, the TL, or the IC, if you want to solve a problem, someone needs to own the problem itself, not just the parts.