There's almost always SOME kind of limit.
But, yes. Let's say you have a particular CPU and a particular GPU, and the GPU is the limiting factor (ie: the CPU can throw data at it faster than the GPU can process it).
You can get a more powerful GPU. Maybe it's still the limiting factor, but less than it used to be. Maybe it's that magical "perfect match" (which doesn't exist, from one game to another, the burden can shift), or maybe it's so much more powerful that it can handle graphics processing faster than the CPU can feed it data.
You're still getting better performance.
It's also very possible, as I hinted at earlier, that in one game, the CPU is the limiting factor and the GPU is waiting on it for more data, yet on another...