Oxymetazoline is different from Xylometazoline, although it was derived from it. Xylometazoline is pretty harmless for adults when not used over extended periods (it is advised to not use it longer than 6 days, but that will cover your typical cold). It is true that if you take it regularly over extended periods, you will have a rebound effect and your nose will get congested when not taking it, so in that way, you develop a "physical dependency", but that's obviously much more harmless than other medication dependencies. Getting off a Xylometazoline dependence means that you'll have to deal with a congested nose for a few weeks...
I don't see from your comment how the risk from congested nose for a few weeks deems it "harmless" for you. Two fully congested nostrils is hell for one night alone, imagine a few weeks of that. A few weeks of terrible sleep, if any. It's torture.
It can also cause permanently enlarged turbinates with chronic use.