In DEO, images fall apart very easily. If you increase contrast too much or decrease brightness, black levels go to gray, and dark shadows can be darker than true blacks. So you are limited in exposure / tonal adjustments as well as limited by the extremely basic color tools.
This is not an extreme example, but if you look closely you can see that Kiara's open mouth and eyes go from black to gray in DEO as you compensate for Lethalhardcore's very low contrast grading. This never happens with HS. If you have the skill, you can get a much more realistic look from many scenes that DEO can't salvage.
And crucially, HS has key frames. So as exposure and camera angles change throughout a scene, you can add points of adjustment to fix everything. In DEO, all changes are global, so it's not worth doing more than the most basic tweaks.
