Out damned spot

We have a small maple tree in front of our house that's at it's most colourful at this time of year. I thought it would make a good blip and it wasn't until I was looking at the piccies on my laptop that I noticed the black spots on the leaves. According to a gardening website:-

"Tar spot is an ugly but mostly harmless disease that strikes several maple species. It causes large, black, tar-like spots on leaves. The fungus lives through the winter on fallen leaves and then spreads to new leaves in the spring when it is moist. Leaf spots start out yellow and evolve into a dark, tar color. Treatment is generally not recommended for tar spot because it is usually not a serious problem."

So if you can't treat it and it spreads to new leaves does this mean my lone maple tree is forever tarnished with the spots? I'd also like a bit more definition around "mostly" harmless.