That misconception was started by those who were fanboys of certain direct draw vapes, and probably never even gave it a chance, imo.
How can a vape be so awesome in 'direct through water' mode, if it can't be excellent in direct draw mode only, to begin with ??
I can answer that. If you're doing direct draw with the stock mouthpiece, and without using a whip, the heating chamber is very close to your mouth. The vapor is still relatively hot when it hits your throat. In my house, multiple users reported a sore throat after a direct draw session. After I noticed the same thing on myself, we started attaching a long glass mouthpiece for direct draw usage, and the sore throats disappeared.
For the best experience with the HA in direct draw, I recommend using a whip or a glass mouthpiece that extends the distance between the heater and your mouth, and allows the vapor to cool before hitting your throat.
Not saying the HA isn't good for direct draw, because I use it that way often. But straight out of the box, with the stock mouthpiece, the vapor can be too hot for many people.
This also explains why its possible for a vaporizer to be amazing through water, but not so great in direct draw.