The hypnotic induction is just a Ritual designed to convince the client that they can be "hypnotized" in a way that matches their preconceptions.
'With that definition you define hypnosis in a way where hypnosis has nothing to do with trance. It's certainly possible to give another person suggestions that do work without having the person in a somnambulistic state. That no useful definition if you want to talk about how certain trance states come with amnesia.
I had multiple times the experience of creating a trance state in someone that causes amnesia without giving suggestions for amnesia and without the person thinking they were supposed to have amnesia.
As for amnesia, stage techniques are awesome. It's really hard to doubt you've been hypnotized when you count your 11 fingers, can't get up from the chair or watch your arm grow to twice the size.
Yes, you can do those things. It's commonly called convincers. On the other hand feats like counting 11 fingers are not phenomena that will succeed for every subject the first time.
This paper, or more often the New Scientist's exposition of it is being discussed online and is rather topical here. In a nutshell, stimulating one small but central area of the brain reversibly rendered one epilepsia patient unconscious without disrupting wakefulness. Impressively, this phenomenon has apparently been hypothesized before, just never tested (because it's hard and usually unethical). A quote from the New Scientist article (emphasis mine):
One electrode was positioned next to the claustrum, an area that had never been stimulated before.
When the team zapped the area with high frequency electrical impulses, the woman lost consciousness. She stopped reading and stared blankly into space, she didn't respond to auditory or visual commands and her breathing slowed. As soon as the stimulation stopped, she immediately regained consciousness with no memory of the event. The same thing happened every time the area was stimulated during two days of experiments (Epilepsy and Behavior, doi.org/tgn).
To confirm that they were affecting the woman's consciousness rather than just her ability to speak or move, the team asked her to repeat the word "house" or snap her fingers before the stimulation began. If the stimulation was disrupting a brain region responsible for movement or language she would have stopped moving or talking almost immediately. Instead, she gradually spoke more quietly or moved less and less until she drifted into unconsciousness. Since there was no sign of epileptic brain activity during or after the stimulation, the team is sure that it wasn't a side effect of a seizure.
If confirmed, this hints at several interesting points. For example, a complex enough brain is not sufficient for consciousness, a sort-of command and control structure is required, as well, even if relatively small. A low-consciousness state of late-stage dementia sufferers might be due to the damage specifically to the claustrum area, not just the overall brain deterioration. The researchers speculates that stimulating the area in vegetative-state patients might help "push them out of this state". From an AI research perspective, understanding the difference between wakefulness and consciousness might be interesting, too.