This is not as black and white as the OP implies.
Most HD channels broadcast on the UHF band, not VHF. Around this area, most of our channels (pre-HDTV) were VHF bands, so many people spent a lot of money on VHF antennas for their roof, some even skipping the UHF grid altogether. My Father-in-law was one of these people. When TV went HD, he lost almost all his channels because his VHF antenna wasn't picking up the right signals.
The HDTV antennas I buy are tuned specifically to pick up UHF signals, and will provide MUCH better reception. After installing a new HD antenna on his roof (which by the way cost LESS than the VHF antenna he had up there), he got all his channels back, and some he never was able to pick up before.
Not everything is black and white. His neighbor was an electrical engineer who also told me there was no such thing as an HD antenna. After I showed him what I installed, and the resulting reception improvement, he went and bought one too.