It is, if they can truly intelligently control the modes.

In much of the US, we are in that time of year where it can be cold in the morning and hot in the afternoon. A common thermostat on full auto mode will be running the heat in the morning and the A/C in the afternoon. Most people opt to set their thermostat for one mode or the other, usually forgoing the A/C in the afternoon, knowing that it will soon cool back down naturally.

Full HVAC control is one of those things that is really hard to get right with just a mostly passive device like this.