I am definitely just talking about ongoing damage in and on itself. Once you add conditions under which the ongoing damage applies, it obviously changes.
My argument is that if you or an enemy takes ongoing damage, it doesn't change its actions. Very theoretically, it could - after all, you can use a Heal Check to allow an extra save. But since that costs a standard action and only gives a single extra save, that option won't be taken regularly. If that is control, it is a very very weak type of control, since the suggested alternative isn't that great.
Area effects are "control" because they tell the foe "don't bunch up if you don't want that damage". Immobilized is control because you can not choose to move. Daze is control because you can't move and attack (generally). Stun is control because you can't do at anything at all. Dominate is control because you do what someone else tells you. Slowed is control because you cannot get to any place. Restrained is control because you have to spend additional actions to move or stay where you are. Challenging/Difficult terrain is control because you limit how far or if it all a creature can move.
But ongoing damage doesn't limit your choices.
But I might have to correct what I said previously. Monsters using ongoing damage might actually gain some "control", since the PCs have typically more options to make extra saves or negate the damage otherwise. These options are still limited, so they have to choose whether they rather save against some ongoing damage or against another condition, or whether they rather have some resistance against the ongoing damage or another damage type.
But if no such powers are available (common for monsters), there is no real limitation of choice, it is merely extra damage.