Yes, in many instances, and in the best of times, we can function without denominations. But we are not always at our best, taking into account our temptation to turn in upon ourselves (and the reformers defined sin in this way) and the complexity of creating and sustaining community. I am convinced that every church and every member of the clergy, over a span of time, needs to belong to a denomination.
Interesting post on Christian Century by Kenneth Carter on why congregations need denominations. I’m sympathetic to what he says. My own congregation doesn’t have a denomination, and is unlikely to ever have one again, after being mistreated by the hierarchy and leaving en masse. I think it’s healthy the way my own church has cultivated strong ties to a wide variety of congregations of various denominations in the area. We might even be well connected enough to have the help we would need from outside in times of conflict. That said, I think denominationalism or some other co-operation is something the church overall is poorer without.