Tim O'Reilly makes a good point here: https://plus.google.com/107033731246200681024/posts/aZSZCsAc... :

"It isn't really Vim's 20th birthday. It's a lot closer to its 35th!" Because of course, vim is really just an extended and improved version of the venerable vi, the first screen-oriented editor for Unix.

While the article starts out with a history of vi, it somehow treats it as if it were a grandparent, rather than the template for what remains. The core design of vim reflects the design insights of Bill Joy, not those of Bram Moolenaar, who refined and updated them."