There are so many odd facets of it with interesting implications; like did you know exposure to sex hormones actually contributes to the atrophy of the Thymus over time? This is posited to have some relation to the increased likelyhood of developing autoimmunity 0roblems as we get older.
Also, not all T cell lines undergo adverse selection in the Thymus. There is a smaller population of more autoimmune sensitive cells that develop and specialize in the extremities. It is theorized this is evolutionary selected for because there is a tradeoff between being able to develop to a wide variety of pathogens, and being free of auto immunity. So you keep a small group of possibly autoreactivr immunity cell lines just in case. This is theorized to explain the prevalence of autoimmunity issues in the extremities being relatively common.