Their experiences are based on processes inside their own oxygen-starved brain, and the accounts they give are untestable against hard evidence. No-one has ever truly returned from the dead to tell us what it's like. No-one has been dead for a week or a month or a year and come back to tell the tale. We are told that many accounts agree with each other and with texts like the Tibetan Book of the Dead. But we are not told of the accounts that do not agree.
Death is real death.
All our direct experience tells us that souls die with bodies. As waters fail from a lake, and a river wastes away and dries up, so man lies down and rises not again. When parts of the brain are damaged or removed in operations, various functions disappear and our mental capacities change. When all our brain functions cease, the available evidence suggests that all our individual consciousness and mind activities cease. But the onus is on those who claim survival after death to prove it conclusively.