Keen Observer wrote:
Why don't they go on their missions after ... BYU? I mean, except for the obvious age advantage reason?
I took the liberty to weed out the fluff in order to focus on the essence of your question, despite its insincerity.
Perhaps It can be answered by a Keen consideration of the following question.
What is the purpose of college?
Imagine an athlete finishing up their college career with enough talent to go pro and trying to convince potential sponsors to sign them knowing they will be taking two years off to serve a mission. Implausible, in all likelihood the sponsors would walk away. Upon return, now you have an athlete who is out of shape and no longer has the collegiate platform to build up and show case their running talents.
Envision a graduate trying to convince an employer to hire them when they graduated two years prior and have had no job experience since then. In all likelihood recent graduates fresh out of college would be prioritized by prospective employers.
Picture someone developing a relationship with a potential spouse during their college years with the idea that not only do they intend to delay marriage until after graduation, tack on an additional two years after that with limited contact due to their commitment to serve a mission. Another far-fetched scenario.
But no, let's turn a blind eye to any/all of the reasons listed above. Espousing a defective take that Obviously the decision to go on a mission earlier is simply a crafty, failproof plan to ensure an advantage over future competition.
Right.... Back to actuality. The longer someone delays their decision to serve a mission after high school, the more implausible it becomes.