I don't mean "awkward" in any sort of "feeling" sense, but in a very straightforward game design sense.
To run with the examples that have been mentioned a few times now - a Joltik is 4 inches tall. A Wailord is 47 feet tall. That means that a battle between the two of them would be a battle between something the size of your hand and something the size of your local Home Depot. If the camera zoomed in far enough that you could actually see the Joltik, you would only see, at most, a tiny fraction of the Wailord - no more than a bit of blue - the equivalent of one brick in the wall of that Home Depot and certainly not enough to even be able to tell that it's a Wailord. If the camera zoomed out far enough to see the Wailord, the Joltik would be the tiniest speck of dust, impossible to see. Either the game would have to stay with one or the other, so you'd never see the other one, or it would have to constantly zoom back and forth, from one to the other. That would be, either way, awkward.