Yea, the evolution of vascularity in plants let them get off the ground in the first place (meaning being taller than a few inches). Vascularity is the first big jump plants made after leaving the water. From there, being taller means outcompeting your neighbors and spreading your babies further. When you have that double whammy of more food + more babies, you get a selective pressure for taller that never really goes away. This is why multiple families have species that have arborized and have continuously done so over their evolutionary history. If the niche is empty, something will jump into it, often sooner rather than later (on a deep time scale) which is basically the whole idea of convergent evolution as a whole.