In the original pilot script, before they got NPH, there's no mention of the blog. Then again, they did write the character more as a heavy-set Jack Black/John Belushi type. Barney's geekiness didn't come into play such as his tendency to make up words and say things like "BRB" until Neil was cast.
Me, I think Barney's Blog is a tribute to Neil's days as Doogie Howser.