I'm not about to "bad mouth" the .30/30
But, it's popularity and performance compared to other cartridges has nothing to do with it's popularity.
It's the rifles it's been chambered in, notably the Winchester M94, their relative cost compared to say a bolt-actioned .30/06, and handy-ness which is hard to quantify.
The lever action rifles until lately have been better "values", were reliable repeaters (as contrasted to some semi-autos) and the lever-actions have become synonymous with "DEER RIFLE"...
that's why the .30/30 is more popular....
I've killed about the same number of deer with the .30/30 as .35. The .35 is the more effective cartridge... no contest. But, the .30/30 is no "slouch" as I was led to believe by the "gun scribes" of the '60's and early '70's.
It was by "shooting deer" and seeing thousands of hunters annually "bringing home the venison" that I saw through the "hype" of the "marketing efforts" of the gun magazines.
And, shooting rifles and shotguns "left handed", I vastly prefer the lever-action to all others.
Both my .30/30's are "lever-actions"
Both my .35's are "lever-actions"...
But, neither the .30/30 nor .35's quite match the .338ME.... but that's another thread for another day.