A half wave dipole is doable but requires a quarter wave matching section (tuning stub) to match to coax. Think about a J pole antenna, same thing. The biggest problem you run into at HF is that the matching section is usually only good over a narrow frequency range and adjustment of the stub can be a royal pain. Even then, you would still want to use open wire line or ladder line as a feeder.
As WIK pointed out there are easier ways to get gain, and a good match with a wire antenna than a full wave dipole. I just didn't want you to think it couldn't be done. It can, but not as easily as some other antenna configurations.
If it weren't for Philo T. Farnsworth we'd still be eating frozen radio dinners.