The urban area of DC is much larger than literal Washington DC and many places there that are technically suburbs certainly do have skyscrapers. For example, "Crystal City", which is technically in Virginia but functionally part of DC.

https://en.wikipedia.org/wiki/Crystal_City,_Arlington,_Virgi...

Washington D.C. has a height limit for buildings[1]. I think the article was just mentioning it as an example of an expensive city, not trying to call it a skyscraper city.

[1]https://en.wikipedia.org/wiki/Height_of_Buildings_Act_of_191...