Yes, then parents can give the device to children, turn on whatever restrictions based on those ratings, and have it work, even if the kid is trying to get around it by doing all those things.
This is not only intended to defeat 5 year olds, but 14 year olds.
If 500px would prefer to turn that switch off for everyone, then 4+ is possibly the correct rating. If they do not, then the correct rating is 17+.
The only people it prohibits from getting the app, by setting to 17+ are those whom have another person setting 17+ as inappropriate for that user.
You do know the web browser and pretty much any apps can be turned off in restrictions right? You can give the thing to a 4 year old, and the only thing you have to worry about is "will they break it" once you've locked it down correctly.
500px mislabeled their app, and as a result were allowing industrious young people who were otherwise restricted to find stuff like http://500px.com/photo/10228807 (Which I don't view as harmful PERSONALLY, but LOTS of people would find that inappropriate for a kid).