Some very questionable/poor groups here.
The DiCaprio group is just silly. No way anyone could possibly link those.
The royal titles group is just that, royal titles. Like the DiCaprio group no one is going to be able to link them as the first part of musicians names, it's just royal titles.
The hated jobs group is just about ok, I made the link there, but it's also a subjective thing and with it being in there with 2 other groups that raise questions, it's all just a bit of a mess.