If you want to make Game Theory collide with reality, the actual convergence to an equilibrium is only one of many venues where there is a large divide. Other assumptions of these models - from rational behavior to uniform prior assumptions - are equally problematic.
Game Theory models are nevertheless very helpful because they require you to actually lay out your assumptions or - when you observe something else - reason about "what else is going on" in any of these areas. As it turns out (as another person has said), it is also immensely helpful when designing mechanism (i.e. games) like a Steam store or an ad auction, which is why tech companies hire quite a few Game Theorists.