This is making a lot of assumptions about what hypnosis can be capable of
6:04 PM
It's less likely to have a tulpa through using hypnosis just once, but possible. Though you would have to be relatively susceptible to hypno or plurality prior to that(edited)
6:06 PM
Some have even accidentally gained unwanted tulpas through hypnosis not made for the purpose of creating a tulpa. Said hypnosis was structured in such a way that it lead to the creation of a tulpa despite not being intended to do so(edited)
The "willing listener" idea is spread a lot for the sake of making hypnosis seem "safer" and less "scary" to people coming into it. It's not entirely incorrect, but there's more nuance to it. It's very hard to get into a trance in the first place if you are uneasy or don't want to be hypnotized. You need to be willing to be guided into a trance, but once you are actually in that state of mind you have less control over things in general. It may sometimes be the case where if you are suggested to do/think something that you are heavily opposed to it may snap you out of the trance altogether, but if your trance is deep enough you might not be "there" enough consciously to have that reaction. However, that actually has nothing to do with why certain hypnosis recordings can accidentally create tulpas. It's well known that someone can create a tulpa without even knowing what a tulpa is. Said recordings do not mention tulpas and the creators of the recordings likely had no knowledge of tulpas. Tulpa creation resulting from them was an unintentional side effect.
6:29 PM
I don't know where you get the idea that hypnosis is "incredibly limited"
It makes it limited in that it can't be "weaponized" like some people claim, and it's only really effective on people who are susceptible to suggestion (but that's a given)
There have been cases of hypnosis getting rid of physical issues such as warts. Similarly how placebo is able to do so. Though hypnosis and placebo aren't the same thing. It's capable of some pretty cool stuff. Most of what hypno can be do can also be achieved with conscious effort, but hypno is different in that it makes things easier as long as you're susceptible to it
Even if someone is willing, hypnosis wouldn't be able to do something like, say, make them act differently for a long period of time, or something similar