Sometimes forgotten in this debate is the role played by cordite. It was very sensitive to heat, hence the emphasis on low pressures. Modern powders are far less sensitive to heat, hence the success of all those "high" pressure cartridges such as the 30/06 amd the 300 Magnum.
The famed African heat, too, is famous, simply because it was compared to the English climate, where the cordite loaded ammunition was manufactured. Here in Australia there are lots of places where the climate is a hot as those places in Africa under discussion. No pressure problems here, at least with modern powders.