If you look up Card Game, Scroll down for a while, you will see a Hopscotcher named Me with no avatar, I found some other games made on Hopscotch and when I play the games, Hopscotch crashes?! It is so weird, The Hopscotch Team, do you know who this person is?
These things happen because they use an old version of Hopscotch and never updated because:
1) there is no avatar because avatars and accounts were added in, and they wouldn't have it if they used an old version
2) the games crash because I think it is so outdated the system can't handle it
3) this is also why you can't view their account, because they don't even have one
So don't worry!
Yes @CreativeCoder is right! Usually these people don't update it which doesn't allow them to get the update after that but it's most likely that they deleted their account, because iPads can update an app before you want it too.
Interesting to know...