The Greeks in the Homeric epics are armed with spears, swords and bows. The spears can be used for thrusting, but are also often thrown. We don't know for certain if this was really how they fought; the heroes of Homer wield weapons that are deliberately described as superhumanly large and heavy, so actually throwing them would be impossible for a regular human being.

If we accept Hans van Wees' theory that the weapons reflect real Early Archaic equipment that has simply been "scaled up" to look more heroic, then we may assume that the Greeks of the time (early 7th century BC) really did use spears that could be thrown as well as used for thrusting, and that the fighting style seen in the Iliad and Odyssey was the actual Greek practice. Dark Age and Early Archaic vase paintings of combat tend to show warriors armed with throwing spears and swords, and riding into battle on chariots. If these are the same warriors envisioned in the epics, we can imagine that such multi-purpose weapons were indeed common.

On the other hand, if we believe that the epics reflect a much more ancient oral tradition containing evidence of earlier, Mycenaean fighting styles, then we're in the woods. It's hard to pin the epics to the historical period in which they are supposedly set, since Late Mycenaean infantry doesn't seem to have used shields, which are common in the epics. But the fact remains that we don't know exactly what period of warfare the Iliad and Odyssey are meant to portray, and that there is internal confusion on the issue (with some very clearly Mycenaean equipment thrown in among the Early Archaic armour and shields). To make matters worse, as I said, the descriptions of combat in the epics are deliberately exagerrated to show that these are heroes from the mythical past whose size and strength exceeded those of modern people. So should we even look for a historical period that fits the way they fought, or should we take this all as fantasy combat, much like the pew-pew guns and laser swords of modern scifi?

Whatever we choose to believe, the least we can say is that the fighting in the epics is internally consistent. The spears are not simply javelins, and therefore using something like atl-atls wouldn't make sense; the throwing stick would get in the way of warriors using their spears for close combat. In the later Archaic period, before Greek heavy infantry fully specialised in hand-to-hand combat, the Greeks would attach throwing loops to their spears, which had many advantages over the use of atl-atls. It allowed them to use their spears for either purpose - throwing or thrusting - without requiring them to carry the launcher around. You can see these loops on the spears of the proto-hoplites on the famous Chigi vase (c. 650 BC) (they are highlighted here).

Once Greek heavy infantry had standardised to the hoplite with his heavy thrusting spear (in the course of the 6th century BC), specialist light infantry fought with javelins, all of which would have been equipped with a throwing loop.