Yup EQ wise with rotten pick-ups and a Cr&p Guitar you can EQ till the sun burns out and you still have what you started with.
When plugging into an amp you get what the designer gave you and then the sound of your cr&p guitar and pick-ups.
When you plug into a modeler you have many more options than the 1 or 2 channels of an amp for many ,many more unique sounds to use as your signature sounds..................
But it all starts with a quality instrument,its got to sound good before you start to tweak.
Then it's tweeeeek till your hearts content!