It's simple:
most golfers back then sucked, just like most golfers today suck. But they didn't mind so much back then, 'cause if they thought of it at all they considered themselves 'sportsmen' who needed a daily walk/constitutional, while today we like to pretend we're 'athletes' who love/crave competition. President William Taft was a terrible golfer, but that wasn't the point; meanwhile President Trump is probably a pretty good golfer, yet critics suggest he's fudging his handicap. So the result: the MacKenzie-type courses being built today play like his original golden age classics did back then -- but only IF we were playing them with all the advantages of modern equipment.