Also from Shankman and Thanissaro in "The Experience of Samadhi: An In-depth Exploration of Buddhist Meditation"
RS: There are examples in the suttas of people attaining at least some level of deep insight of awakening apparently without jhāna or deep meditation practices.
AT: These are the cases where people gain awakening while listening to teachings. But we don't know what their minds were doing as they sat there listening. Usually the teaching was pointing directly to something going on in their minds, so they started observing their minds, entered concentration, and gained release.
RS: There are teachers who tend to shy away from jhāna as being not necessary at all and even a potential trap.
AT: The Buddha wasn't one of them. There are some people who tend to be psychologically unstable and have to be very careful about how they handle states of concentration, but in general, if you have right view about jhāna, it's not dangerous at all.
Now there are some people who say jhāna isn't necessary, that it can be a hindrance because you can become attached to the experiences and mistake the aruppas for Nibbāna. But there are lots of things you can mistake for Nibbāna. If you're doing what you think is vipassana and you hit, say, a state of nonperception-- you may think that's cessation, the end of suffering. But the danger doesn't lie in the state. It's in how you interpret it. No matter what your technique, if you're the sort of person who tends to overinterpret your attainment, you're going to hear in that direction no matter what. Some people tend to be very good at denial, they're good at not seeing their own defilements, and they can use the one-pointed kind of jhāna to exacerbate the problem. But they can also do that with any of the vipassana techniques.
"What holds attention determines action." - William James