Can anyone tell me why this flight was delayed for 7+ hours at LAX?

Definitely not complaining at all as the delay allowed me to get home earlier. (Missed my original 5:25 pm flight after coming in from HKG due to a 2 hour ordeal at LAX Immigration/Customs.)

But, there were a lot of people who were not accommodated on earlier flights and had been at the airport for 11 hours.