I'm sorry, but where does the OP reference anything about practising interviewing? In fact, his point seems to focus more on fundamentals than anything.

My takeaway was along the lines of removing the junky presentation layer (whiteboard, etc.), and making sure that you SHOW your fundamentals. Working on Project Euler helps build those fundamentals, writing code comfortably during your interview helps show your fundamentals. In terms of presentation, I didn't feel like he was doing 'window dressing', you definitely want to show your interests, projects and your opinions, these are part of the fundamentals.

No matter what, there is always a base line of presentation that you must meet in an interview to show your fundamentals. I feel like this post is encouraging you to meet that base line, as well as increase your fundamentals.