I've seen them try, and the plays they choose show that they don't understand what they are looking for. It's a lot more nuanced than "well they both ran a lot of ground while people tried to tackle them."
Fields is a fast and powerful runner. There are a lot of plays where he uses that power and speed to take advantage of space the defense gives him and break off a huge run.
I've been trying to explain this to Bears fans for three years: fields is a pocket passer, not an out of pocket improvisor. It's just that when a play breaks down and he takes off, as all pocket passers sometimes do, he's ungodly fast and strong.
That's not even a little bit the same as Williams' freakish in-pocket abilities. His footwork is as good as it gets, allowing him to move in any direction instantly while maintaining an athletic base to throw off of, and he combines that with an unbelievable instinctive understanding of not just where the space is and where the pressure is, but where they are going to be.
Much like his off-platform throws, I think it's hard for everyone to appreciate how good his footwork in the pocket is because he makes it look so easy. He's constantly making little adjustments to put him in the best spot, even as that spot is constantly changing. On the touchdown scramble from the moment he hit the back step of his drop to the moment he exited the pocket, 3 seconds elapsed and he changed directions 6 times, all of them justified by the changing situation around him.
He also has an intuitive understanding of what's going to happen in the pocket before it happens. He's not just reading to open or closed space in front of him, he's reading blocks and shifts that about to happen and moving in anticipation of them