I'd like to look at this historically. The .30-30 has likely killed more game than all modern cartridges combined. Going back further, the .44-40, the .44 mags grandfather, has likely killed more game than the .30-30, and likely mostly with black powder and soft lead. This is not because they were superior hunting rounds, but because they were the best compromises available. There were more powerful rounds than the .44-40 and .30-30 in their days, but both were widely available (and marketed) in fast handling carbines. The .30-30 with it's new fangled smokeless powder was a quantum leap forward in range and trajectory, but not necessarily in stopping power. The 30-30 and other medium range cartridges, as well as their old and slow forefathers, held their own until after WWII when optics became readily available and affordable and hunting ranges began to outpace the .30-30's ballistics. When iron sights were the norm, the .30-30 was considered ample medicine for moose!
Now fast forward to modern times. .30-30 and .44 rifles still do kill deer. They do it quite efficiently under 100 yards, and in the case of the .30-30 can be pushed a bit farther. When you add a scope and a competent marksman, rounds such as the .308 and others can reach out significantly farther and still make ethical kills. They may be hitting as hard or harder at 300 yards as the .30-30 is at 100. The latest rage is high BC bullet/cartridges such as the 6.5 creedmore. They push a relatively heavy and skinny bullet at a decent velocity. The aerodynamics of such a slug carry energy more efficiently over distance, so they hit harder at distance. I don't want to get into that debate here, but basically your .30-30 is handicapped further at distance due to the blunt bullets that must be used for tubular magazines.
Bottom line: If you wish to go out and kill a deer at relatively short range, your favorite Win 94 will absolutely do the job. A .308 will do it with a little more margin for error...it brings a bit more kinetic energy to the table, and retains energy better at distance due to the "pointy" bullets used.