Your own perception of giving/receiving a statement is unique to your brain, not the meaning you are trying to convey. Society teaches us methods of interaction from birth- language, reason, images, etc.
We learn these methods to have a common system of interaction. For example, you are taught how to write/read the word “apple” and link it to an image/object. Your perception of “apple” always stays constant and the method you use to express “apple” remains constant. However, when you express “apple” to another brain or another brain sees an “apple”, that brain's internal perception is entirely different from yours. You don't realize it because everyone is taught to express their perception in a standardized way.
You can also think about it in terms of colors. We are taught which color is which from a young age but there is no way to know how each brain perceives color. Your internal perception of “red” may be entirely different from another brain's perception. And when the other brain goes to express “red” to you with a paintbrush, it picks that common color that you both were taught to associate as “red”.
Even though we have a common system of interaction that makes it seem like we see reality the same way, the internal perception of that reality is entirely different for each person. It doesn't make a difference for most things we encounter every day but when you start exploring “outside the box”, those differences in perception mean everything.
Not really. We can evaluate these so called "outside the box" experiences, compare and contrast them, and then draw conclusions about them. Firstly, if nobody ever reported these experiences then there would be no phenomenon called "near death experiences." If only a few people had them and they were extremely rare, and especially if each reported experience was not anything like the others, then they could be simply dismissed as hallucinations, illusion, reaction to lack of oxygen, etc.
But millions of people have them, and they are a phenomenon that is commanding attention in large part because they are so similar in important aspects across boundaries of culture, age, gender, and time, and most importantly, across the conditions of each experience. Some experiencers truly are in a state of being brain and heart dead, others simply close to it, and others only in a state being threatened with death. There all also many that can replicate the out of body portion of the experience simply through meditation, breathing exercises etc.
The out of body aspects of near death experiences, and the ability to leave the area, and accurately report on things that could not have been viewed while lying unconscious on the operating table, is one of the most compelling arguments in favor of the idea the consciousness can exist outside the body. You say this can be replicated with DMT. Are you saying the DMT allows the soul (ego consciousness) to leave the body? If so, then you have not done anything to debunk the afterlife, you have only shown the means by a soul might extricate itself from the body.
But it appears you do not believe in the existence of a soul that leaves the body after death and continues on in another existence. If that is the case, then how does the DMT give people knowledge that they could not have obtained while lying on the operating table?