I participated in a Twitter exchange following the CIPD’s report – along the lines of who is the biggest problem – rubbish leaders, managers, HRDs or organisations? But thinking it through, I would go for the leaders – as they have so much influence over the approach their line managers take.I think your focus on the nuance is where I would put my, granted non-expert, opinion. I believe what you say about the big impact executives/leaders have in setting and maintaining the management system. The direct boss I do think has a big impact. But it is true that much of the direct boss' impact steams from the system - if they are not a good manager that is usually a system results.
there are clearly a range of factors involved in exit decisions and an individual's line manager is certainly one of these. But I do agree with the researchers, and therefore disagree with Gallup, in that I believe it is the senior leadership which is increasingly the most important of these.
It is rare that the organization does a great job of selecting and developing managers and your manager is lousy and you want to leave. In broken systems (unfortunately many - which is why Dilbert connects with so many) often the direct supervisor becomes the focus of complaints but really they are largely at the mercy of the larger system.
Related: posts from my management blog on managing people - Practical Ways to Demonstrate Respect to Employees - Create a Climate for Joy in Work