I can understand death and pain, I have experience of them and I know how they work. Collectively we don't understand how functioning brains work yet. Brains not functioning quite right is so intangible therefore, that without direct personal experience it is very much 'here be dragons'. Especially as there isn't really a useful frame of reference to even describe such things and no means of comparison to discover what is 'normal' and which parts of any person's brain functioning is outside of 'normal'.

You might suggest, for example, that my perceived believe of looking at this in an objective scientific frame of reference is, instead, tactless and cruel; and not 'normal'...