As others have mentioned, the 30-30 was originally a black powder cartridge. It's other limitation was flat-nosed bullets, due to its being used in tubular magazines. Pointy bullets with great ballistics also make good firing pins,and a chain fire in a tubular magazine is the kind of excitement we can do without.
30-06 rifles with box magazines eliminate this possibility, so the universe of projectiles that can be used expands dramatically.
The .30 Winchester Smokeless first appeared in Winchester's catalog No. 55, dated August 1895. As chambered in the Winchester Model 1894 carbine and rifle, it was also known as .30 Winchester Center Fire or .30 WCF. When the cartridge was chambered in the Marlin Model 1893 rifle, rival gunmaker Marlin used the designation .30-30 or .30-30 Smokeless. The added -30 stands for the standard load of 30 grains (1.9 g) of early smokeless powder, according to late-19th century American naming conventions for black powder-filled cartridges. Both Marlin and Union Metallic Cartridge Co. also dropped the Winchester appellation, as they did not want to put the name of rival Winchester on their products.[3]