And leaves can absorb moisture from water droplets on their leaves. Like from rain or foggy sea winds. Why go through a transport system when the water is right where it's needed?
Water and solute movement in plants:
https://www.ebsco.com/research-starters/anatomy-and-physiolo...
there is a disconnect between the roots and the xylem, its not a throughway, there is a switchover.
Plant Roots and Mineral Nutrition: An Overview of Molecular Basis of Uptake and Regulation, and Strategies to Improve Nutrient Use Efficiency (NUE)
https://link.springer.com/chapter/10.1007/978-981-15-9380-2_...