Enlightenment by doing seated meditation, otherwise referred to as zazen is what Western Soto Zennists believe Zen is about. Having been involved in Soto Zen I can speak for them. Yes it is true. Back in the 1960s, in my Zen robes, I would sit in meditation several times a day with my teacher and the other monk. Yep, I believed I was doing Zen!
But during the Tokugawa period (1600–1867) was doing zazen the main attractor which accounted for Zen’s popularity at the time like it is today? The answer is no. So what accounted for the success of Soto Zen during the Tokugawa period?
The scholar Duncan Ryūken Williams has demonstrated in his book, The Other Side of Zen, things like healing, rain-making, protection from fire, and funeral services contributed to the overall success of Soto Zen. Little if any of Soto’s success was due to zazen—and here is the kicker—nor was its success due to the teachings of Dōgen Zenji. Dōgen’s works were read by only a minority of Soto priests.
What is going on in the West as far as Soto Zen is concerned, is that it has become the cult of Dōgen Zenji and consists in doing lots of zazen. But also, in my humble opinion, Dōgen’s works have introduced metaphysics into Zen, for example, the notion of being-time (有時) without which things, supposedly, would not be things for everything is really being-time. Being-time is also an activity, a flow. Take that away, nothing remains.
Personally, I think Dōgen has missed the fundamental aim of Zen which is to see the kingdom within, that is, to awaken to our unconditioned Buddha-nature which is hidden from us by our preference for the external, conditioned world including our preference for the temporal body of birth and death. All that this preference does is serve to hide our true nature.