I can't see it doing any harm except requiring just a bit more work on your part to make the rows. It may limit your growing capacity to some degree by making rows. If you just leave it flat, you can plant things like lettuce, spinach, swiss chard, etc. fairly close to each other and turn that whole box into wall to wall salad greens.
In a couple weeks when I put in my leafy salad green seeds, I'll flatten the top of the row to 24" and plant 3 rows of seeds and thin as needed when they are a few inches tall. When the plants take off, the entire top of the row is just chock full of various lettuces, bitter greens, arugula, spinach and chard.