As long as there was a standardized, transparent way to emancipate yourself and prove your readiness before that age, I'd support your proposal. In fact, why no

As long as there was a standardized, transparent way to emancipate yourself and prove your readiness before that age, I'd support your proposal. In fact, why not get rid of the "automatic adulthood at given age" system at all so that everyone could attain adulthood only through the emancipation process?