Live/Cut baits are obviously going to produce larger fish. If you are fishing with a live sucker or sunfish, only larger cats can take them down, its pretty simple logic. That isn't to say that large catfish won't ever take liver or night crawlers it's just that the smaller cats that have to rely on their speed will get there first.
On another note, sunfish and shad are not available to everyone. In Minnesota and North Dakota you cannot use any Gamefish as bait - cut, dead, found on the side of the road or otherwise so we need to explore other options... like chicken livers or shrimp - or our cut/live bait would most likely be a large sucker minnow.

No need to get hurt feelings over the subject. We all love fishing.

.... and some of us apparently like holding hands too.