The main issue was “it's sloppy” and “very outdated”. “Sloppy” implies lack of care went into its creation, which is often seen as an attack on the creator(s). “Very outdated” is imposing your idea of what's “new” and “old” onto your contemporaries, then https://en.wikipedia.org/wiki/Chronological_snobbery on top of that.

Apart from that, your comment was a fairly objective criticism. When criticising, you should write down all the things you want to criticise, then (without removing any) re-write it so it's as kind as you can to the thing you're criticising. Especially if you're comparing it to something of your own.