Recently I've discovered something called peat pots. Why should I use them? Why wouldn't I just put the plant directly into the ground? Is there any advantage?
In many cases, it is simply for convenience. However; there are some plants which do not tolerate transplanting. Therefore, to start seeds indoors to get a head start and/ or maximize their strong stocks, people use peat pots so they can transfer them outdoors without transplantation.
One noted example of an intolerant plant is corn.
They're used for starting seeds, and not for putting plants into. Then once the seed has sprouted and grown a bit, you can then transplant the whole thing into soil without disturbing the new roots. There is also no competition from other seeds that you would get if you put the seeds directly into the ground.
The new roots will also grow right through the peat pot if the bottom is kept moist. If too dry, it can cause the new plant to be root bound. So, some people recommend keeping them inside a polystyrene cup.