It was humbling. Like a computer being turned off, and then back on an hour later.
For that time, I didn't exist. It helped convince me that after death there is just.... Nothing.
So it seems sensible to me that General Aneasthesia would feel quite unique in that regard (I have experience it myself) - one moment you're here, the next you're waking up. You don't dream, you don't feel like time has passed at all, it's just kind of a blink and then you're somewhere else.
And that's it - "true nothingness". It's the closest you can get to not existing while still being able to come back.
If instead we found someone who (for whatever reason) believed that they just popped into existence, as if from a puff of smoke, at the age of 3... and we did your thought exercise but instead told them "think back to the 3 years before you manifested"...
To that person, it might well seem like a clever idea. "Hey I didn't exist then, but I don't really experience or remember that nothingness!"
Except they did exist, may well have been conversational even for the last part of it, etc.
There's no good way from first principles for me to be sure the same isn't true of myself before my birth. I don't expect much after my death, but like everyone else I'm just going to have to wait and see (or, wait and not see, as the case may be).
I'm just saying this may be a good way to help someone visualize better what it even means to say that consciousness just stops, not that it somehow proves that is what happens.
If death is infinite, to really compare death and anesthesia, we'd need to experience being under for longer.
I think changes in perspective break memory.
Greater changes mean greater breakage.
Walking into another room is a change. sleeping, dying, Weird drugs. Those are also changes.
Also, there is a degree of breakability/flexibility, inherent to the person. Depending on various stuff.
And there are ways to become more flexible too. Less prone to breaking. This leads to phenomena like "lucid dreaming".
I think that's in the difference. When dead, your cells all decompose and start releasing and forming decomposition compounds which flood your brain and body. Not to mention your cells becoming fundamentally broken and unable to do their jobs.
My theory is that there's a fundamental system in the brain that gives us our sense of self gives us our sense of "this is me, and that is everything else". And that slowly goes away to the point where you can't distinguish the difference between self and other and you become everything.