I agree except in the "too busy too blog".
I'd say blogging helps you be concetrated on what you are working on. While writting about it you rethink your choices etc.
It's also not that time consuming, if you are not doing it every single second that is...
if the posts are related to the things you are working on, then writing about them, during a break, it could help you not get distracted in case you did something else totally irrelevant.
It's still a bad idea to associate blog-writing skill with technical and even interpersonal skill. It's also a bad idea to make too many assumptions about the reason why someone might choose not to have a blog. A guy with a family might not want to risk getting the wrong sort of attention, for example.
i guess how much time is spend depends on the nature of the blogging someone is doing and if there are any good thoughts to communicate. When someone has an audience I'm sure then don't feel it's a waste of time.
It's also not that time consuming, if you are not doing it every single second that is...