Why LDS leadership is a gerontocracy
 

Psychologically, it's much easier to unquestioningly follow the commands of someone older than you. So the strict seniority-based promotion scale serves a practical purpose.

But I've always liked the drama behind the college of cardinals, smoke signals, etc.

"strict seniority-based promotion scale"?

Counter-examples:
- Faust in the First Presidency
- GBH in the First Presidency during ETB's era
- Bednar in the 12 (many more senior members in the 70)
- Alvin Dyer in the First Presidency (was never even a member of the 12)
- many, many other examples