Ouch. I hope when I post something to HN I get constructive criticism or even skepticism but I would really not want commenters recommend other similar projects or ideas.
Sorry, I thought I provided constructive criticism.
This project has been up since 2011 (check their blog), so I thought they must have known about Doodle already, and can solicit further feedback on why someone may prefer another project than theirs.
Regardless, I think it is always worth mentioning competitors and related projects, either for the creator to get ideas from or to see how they can work to differentiate themselves.