If anything, this article demonstrates the great design of reader comments - almost all of them disagree with the OP and make better reading than the original post!
I think there is a fine balance between being "strung along" and gradual engagement.
For instance, if I were to use an app to share photos (a la flickr), and I was invited to upload a bunch of photos then be presented with "Ok, now you've got to sign up RIGHT NOW or we'll delete everything you just did" - that's sorta missing the point. That's less gradual engagement and more impending doom.
The implementation of the chatbot above seems to be more along the right lines, though. The holy grail perhaps would be allowing the user to fully engage with the service without even realising it.
I wrote a post about setting up IIS 6 and PHP (oh, my misspent youth). It was split into 3 parts; except I never got around to writing the third part: the copy-paste author made an attempt at writing it for me! How nice of them ;)
Shame it was full of spelling and grammar errors, and entirely devoid of any useful information. Nice try, though.
Hurray for blog comments!