Yank arms companies design their calibres to create niche markets. Think 6mm BR and .243. The invention of tapered barrels means the 6mm BR does exactly the same thing with a smaller, lighter, cheaper cartridge. They also design them for profit. Think of the .30 and its replacement, the .223. Same range, lighter projectile and a much larger cartridge. The greatest cost is the cartridge and running cost is the greatest long term expense. So let's go the other way:
.200 calibre: a 90gn projectile at 2700-3000fps, tubular cartridge with a steep taper, guns with a 1/3 tapered barrel and a range of interest of 400m. A 70gn deer projectile at 3000fps and a 55gn hollow point at 3250fps. A high twist rate. Thus replacing the .222 and the .22-250.
+ a long 90gn projectile at 3000fps will be flat shooting. That's how aerodynamics works.
+ a tubular cartridge is cheap.
+ a steep taper prevents jamming, particularly at low temperatures (see the trouble the 6.5 Creedmore has in semi-auto. Constantly jamming).
+ a tapered barrel increases the role of the barrel in accuracy, there's also the size of cartridge, projectile design and length of barrel (discounting environmental factors). This allows for a smaller, cheaper cartridge. At only 400m there's no point in the extra weight of a full taper.