Bob
The amateur controversy in Britain you're speaking of took place in late 1908. There were two complaints from the pros - 1. that some amateur club members were buying golf balls in bulk and selling them to their fellow members at low cost, undercutting the pros and 2. amateur links architects who accepted a fee were in violation of the amateur rules (the amateurs were also stealing a lot of the top commissions). The first complaint was considered legit; the second was soundly shot down and never got anywhere. To my knowledge the R&A did not amend their amateur definition (which was written in 1886 prior to the first British Am) until sometime after WWII (on second thought they may have tweaked the caddying rules slightly in the 20s). Designing golf courses for a fee was never considered a violation of the rules as written. Interestingly caddying was a major focus of those early amateur rules.
Amateurism in sport (and other endeavors too) has always been a big deal in England. Amateur sport was considered the highest form of sport, and because of that there was a long history of abusing the amateur rules. One of the best examples was cricket, which may have been the most popular sport in the late 19th and early 20th C. Guys like WG Grace made a fortune in and around the sport and he was considered an amateur his entire career. Shamateurism was a common term in those days. I think there is evidence of some animosity toward the British amateur movement in the USA, which may have had something to do with the rule changes regarding golf architecture.
On the other hand the USA has had there own series of shamateurs, Travis being perhaps one of the first and most blatant. The rules change may have been an attack on him too. One gets the impression he was not always the most popular fellow. But there were others, I think it is pretty clear Ouimet did abuse the system, and Bobby Jones too.
I wonder who were those five or six amateur golf architects Verdant Greene is referring to?