[quassnoi]

This is very often "expected to work". Just search StackOverflow for FIND_IN_SET. Here are just three random hits:

http://stackoverflow.com/questions/4037145/mysql-how-to-sele...

http://stackoverflow.com/questions/3946831/mysql-where-probl...

http://stackoverflow.com/questions/3734161/mysql-select-wher...

None actually "blames" MySQL for that. The article just describes what comes to the beginning developer's mind first, and tells the correct way to do that.