In the future, before saying such snarky things (which are of little value to the discussion), perhaps you should read the comment you are responding to. The first sentence of my comment limited its scope to the location issue:
What exactly is wrong with excluding certain areas from seeing your ad?
As much as you might think you are being clever by just saying "Oh, I'm just excluding AREAS, not people" you are still running afoul of the law since you are effectively using zip codes as a proxy for race. This has been tried before and the courts aren't really fooled by it.
So, no, there is nothing inherently wrong with excluding certain areas from seeing your ad, unless you are using the area exclusion mechanism as a proxy for excluding based on race/sexuality/religion or some other protected status.
The point is that you are not necessarily running afoul of the law by excluding zip codes in the absence of other evidence that you intended to discriminate. Excluding poor neighborhoods from seeing a $10 million home listing is common sense, not discrimination.
Often such arguments are just trying to prevent regulation, but there are situations where regulation wasn't written with this tech in mind and therefore doesn't quite apply. At the very least, the discussion can be fruitful.