"eliminating naps": beyond obvious.
"not exercising at night": duh.
"avoiding caffeine, alcohol and tobacco before bed": *long* before bed for some of us, even. Caffeine after 4pm is guaranteed to mess with my falling asleep that evening.

"Got problems? Who doesn't? CBT-I teaches an insomniac not to stress over these issues at bedtime, which is guaranteed to keep you awake" : no kidding. But for someone suffering from generalised anxiety like me, this is useless advice. My brain WILL ruminate at night, no matter what I do to distract it. Xanax is the only thing that makes it slow down enough that it can fall into sleep when sleep flies by.

"making sure the room is dark and cool": dark or not makes zero difference to me, while cool (even cold) is absolutely necessary.

"and only using the bedroom for sleep and sex": that would be pretty much the best way to ensure I never fall asleep again in my bedroom, since it would turn it into "that place where I HAVE to sleep". Studies about insomnia should definitely take into account things like the fact that many insomniacs utterly fail to fall asleep in their perfectly-prepared-for-sleep bedroom for hours - yet fall asleep 20mn later on the couch, in front of the running TV, with all the lights on. So much so that some insomniacs pretty much never use their beds for sleep, going straight to "bed" on their couch with the TV on when it's time to sleep.

It's good that insomnia is finally being looked into seriously, but the researchers have better not fool themselves: this one will prove to be as complicated, multi-causal, and multi-faceted, as depression itself.