“Nihil de nobis, sine nobis"
Latin for “nothing about us without us”; this means any decision for a particular group, should include that group discussion members. It is not to say the expertise of the other team members are not valuable but rather to have several or a group of people who have lived the problem is invaluable. A person can only assume and interpret the lives of those around them; as detailed and correct an interpretation may be, it is not a first hand experience but a fabricated one built by filling in the blanks. The outcome is many products or services target a problem at the surface level and gloss over the ‘small details’ either unthought of or deemed unimportant.
Such as the design of a prosthetic. Many prosthetics are made plain with a serious outlook that reminds children of their difference among other children and their lack of limbs to be a serious problem. Creating a more kid friendly design, such as an Iron man arm or one made out of legos, encourages the child to accept their lack of limbs with a positive outlook making the prosthetic more desirable. That they have something cool that other kids do not rather than one limb less.