Home oxygen concentrators are for home use because they can only be plugged into an AC outlet. They're also usually larger than portable concentrators, so you wouldn't want to have to transport them around, anyway. Even so, stationary oxygen units are still necessary and make the lives of oxygen therapy users easier.
If you only need to use oxygen therapy a few hours out of the day, a stationary model might be a better decision, because portable models can be much more pricey. You might only need to use it overnight, and you don't plan on doing a lot of traveling to other places where you would be staying overnight. If you would generally only be using your oxygen therapy while you're at home anyway, a stationary oxygen concentrator is a way to go.