[nollidge]

> There have been many choices in grammar that have been decided almost arbitrarily by higher authorities

Just because somebody makes a decree about grammar doesn't mean it'll be widely accepted, any more than an organism obtaining a genetic mutation means it'll become spread throughout the population in subsequent generations.

My point is just that there wasn't any overarching plan. People design their own use of it, but whether or not that becomes popular enough to be considered "the rule" is analogous to natural selection - messy, convoluted, frequently arbitrary, but good enough.