Is blogging killing planning? Well, as a non-planning blogger (but someone who wants to become one, by hook or crook) that reads a helluva lot of ad blogs, I don't think it will.
Also, there's a concern that we forget about the role of 'proper' qual research in the planning cycle. Well, I very rarely read blogs for their statistical content, unless they are the brilliant Indexed. Looking at stats makes up a proportion of my current job, and I think the role of reading blogs for me is to (first and foremost) unwind, and secondly to improve the amount of opinions and advice I have at my disposal. Others may have it t'other way round, but hey - I like to learn and relax.
Essentially, if someone really is junior and trying to get into planning, I think they'll have realised that the job isn't just about reading blogs for a living, and certainly won't take blogs to be the gospel truth - more a place to store thoughts and act as stimuli/a forum for debate, depending on your point of view or requirement for the blog.
Download my second Podcast here if you don't want to scroll down - it's in the sidebar. Featuring more random tuneage. For some reason the link auto plays the tunes, but just click 'stop' and download it normally.