It's actually that they aren't special. With gametes the body cares about making sure things work out well, and you only need the one embryonic stem cell to be

It's actually that they aren't special. With gametes the body cares about making sure things work out well, and you only need the one embryonic stem cell to be issue free (discarding any with mutations) to create a new healthy human. With the somatic cells though you just need one (oversimplifying massively here of course) cell to become cancerous to kill the person, and the DNA repair mechanisms become more likely to fail throughout life