To lead as I have learned requires following and observing people that do good and bad things, and it takes 1-2 years for every year of growth.
A rule of thumb that I would use is that if the government states one can't consume some substances legally as an adult, with the view that on average a person's brain is "not" fully formed. One might presume the same thing as leading life situations ...
Should 19 year olds be in political offices doing things? You betcha, they should learn and experience and do, but as we all know if we use the adage book from last decades 10,000 hours, it takes roughly 5 years to become an expert at a single topic.
So seeing a person try and fail is not a bad thing, but in today's stakes politically, where the nuances in race and sex and finance and socioeconomic issues is so dense that studied academics fail.
I believe our founders saw this and this is why they put the disclaimer in the senate seats of 35 years of age during a time when the average life span was 36.
They used the fact that natural death would limit the position of a senator to 1 term.
So one might state if the original design was meant to allow people with experience to execute the job for a few terms and not a lifetime, and one had one "shot" at it. Would you prefer a 19,39, 59, or 79 year old to run it?
There is no good answer, but we I believe we all agree that what is being done now is horribly broken.