Also, for HF antennas, it is often difficult to get the dipole antenna sufficiently high that the ground will not affect (lower) the impedance. And if the folded dipole is part of a VHF Yagi, then the impedance will be affected by the other elements and will drop.
For HF, it is usually simpler to tune the impedance at the bottom end of the feedline (using an antenna tuner). The extra VSWR on the feedline might cause a slight increase in loss, but usually not worth worrying about (for HF).
Jeff
PS: Ottawa temporarily. VE1BLL/VE3 for a while longer.