With Hetalia in particular there's the problem that the canon is so all over the place. It can be really bothersome to try to find a certain strip or character note, and a lot of people aren't even aware that they exist and won't look for them. Every now and then, I'm still surprised by "new" canon details about about my favourite character when someone on Tumblr reblogs a sketch from 2009 that I've never seen before. It's so much more convenient to head to a wiki where everything is in one place, even if it comes with the danger of misinformation.