The goal with HPA is to have root hairs which are the most efficient eaters. The problem is the roots must neither be too wet nor too dry- keep the roots hungry, but never starving.
High RH/temps inside the pod is a root hair killer. My grow room is not climate controlled and the room has open beam ceilings. This week temps will be 80+ all week. That's ok for ambient temps during veg, but it drives high humidity/heat inside the pod. Also the pod lid needs to be covered with reflective material or the heat from the grow lights will cause high heat/humidity inside the pod, again killing the root hairs.
Good to have leds with HPA in warmer climates. I use HOT5s, which don't throw a lot of downward temps, but the smaller the plant the closer to the lights and, well, 80*s inside the root pod and root hairs will die, or not develop.
Clearly, if you live in more moderate temps, the issues are minimized, but too cold is similarly bad for root hairs.
And so on with the potential obstacles
hth
Don't really want to get any more involved in this within my thread