A lot of the big bands that are capable of headlining are already booked or doing their own tours. The US seems to be getting in on the act and booking similar style festivals so many bands are booked for those as well, Carolina Rebellion's lineup is fantastic.
Originally Posted by dodger0703: “as has been said on a few forums, there are not that many bands nowadays who can headline festivals”
That is very true, the Rock and Metal genres are so fragmented today there are very few bands with enough cross-genre appeal to headline more than one festival each year.