"TEP: How the distinction between pros and amateurs came into being, and the rationales behind it ..."
Shiv:
Something like that wasn't exactly some "rationale" that someone thought up, it was more a cultural and evolutionary thing.
Back in that day, golf, which emanated from the British Isles was supposedly a game of "Gentlemen"! What did the word "'gentleman" mean to them in that day and culture? It meant someone of high birth and consequently education, and obviously in many cases wealth and social stature. That so-callled "class" was also one that in many ways lived under an ethos of "Noblesse Oblige" (at least in theory
) which meant the moral obligation of the rich or highborn to display honorable and charitable conduct---and generally towards ALL!
That conduct included many things about their lives--business, politics, and even in many cases their recreations, such as golf. There's no doubt that golf in those early times of clubs populated by these so-called "gentlemen" and their families played golf with anyone who was good enough or interested enough. The old saw that in that culture Kings played golf with cobblers and their employees who worked with golf for them is true.
However, that class in almost no case at all invited the rest of the world they dealt with so closely and so charitably in all those thngs mentioned INTO THEIR HOMES. And that included inside their clubs (clubhouses)---which to them was somewhat of a communal "home" for that class---an extension of their own homes--eg their CLUB!
As kind and honourable as they felt they morally should be under "Noblesse Oblige" to all people particularly those they understood to be less fortunate than them it was always understood that their homes and clubs is where they closed the door on the rest of the world. Maybe they felt that was their only insulation---who knows?
This entire ethos was carried over to the early culture of the United States as so many of those great early clubs were bastions of the so-called WASP world---those American descendants of the British Isles and in many ways its aristocracy.
The early golf "pro" in that era was someone who worked for them or their clubs---generally doing everything in that early simple world of golf---making golf clubs and balls, greenskeeping, administering the club or pro shop and since those early pros worked so completely in golf they obviously became many of the day's best players and the teachers of golf.
That's the way the culture evolved and that's why even into the middle of the 20th century "pros" were often not allowed into the clubhouses of these clubs.
When we look at that culture today some may bridle and take huge humbrage over it. But back then it's just the way the world worked and most who lived in it understood it and accepted it. It was an age of huge social classifications and stratifications.
However, we can see that over time, perhaps due to the game itself and eventually the curiosity with perfection in it as well as eventually the time when real money could be made in it all that changed---and we are now in an era where pros are no longer classified or stratified socially or culturally and the greatest of them have become world-wide icons who can own their own golf courses and clubhouses if they want to!
And through all that and to this day the idea of the "amateur" golfer was always part of the game. The person who played the game only for the enjoyment or love of it. Through all that time playing the game for the enjoyment and love of it and taking any money whatsoever for anything whatever (including architecture early on) to do with it was considered to be mutually exlcusive.