Can you keep a diary and a blog?

Read an interesting on-line interview with a retired British politician- Tony Benn- in which he derided blogs and said they would mark the end of diary keeping and the rich vein of literature that diaries and personal recollections hold for future generations. I keep a diary and blogging doesn't interfere with it - the two are totally different genres. There are things I record in the diary that I would never think of putting on the blog. Similarly, the ability to take a photo on the phone and post it two minutes later provides and immediacy that the diary lacks.However, he may have a point. Anyone under 30 probably thinks that writing on paper with pen and ink was a process that went out with the ark.