A tree in a nursery standard sized root ball does not need staking unless it's on a severe slope or in truly mighty winds. Even then, guy lines should be loose to keep the tree from falling all the way over -- they should not prevent it moving.
What we learned from Gary Watson, author of Principles and Practice of Planting Trees and Shrubs and mastermind of decades of tree growth work at the Morton Arboretum in Illinois:
A tree can be girdled in a year by staking. Even if staking lines are removed before they girdle the tree, by having prevented trunk movement they cause breaks later. A tree must flex to build cell strength.
Also, we learned from Dr. Alex Shigo, author of A New Tree Biology, which captured much of a lifetime of groundbreaking work with the U.S. Forestry Service:
Trees are not like people. If you took an individual human cell and stood it alone, it would collapse. Our cells must be in masses, supported by bones connected to muscles and contained in skin, or we cannot stand. Yet a tree can stand up one cell at a time. Every single tree cell has strength that adds up to the tree's overall strength. Individual cells become strong when they are subjected to pressure as they shift in wind and weather. The cells walls crack but do not break. Then, fortifying lignin is layered over the fractures, which become stronger the same way an archer's composite bow becomes stronger by lamination.