I think this is a valid point, in that it serves as the other side of the coin to the arguments of your parent poster. Other than transportation and carrying ability, cars also amplify things like consumption of energy, physical space, and so on.

I think this is probably why the question in the original article, "What should a city optimize for?", is really the MOST important one to answer.

If your goal is to keep housing costs low, for example, then presumably you'll want to optimize for space (based on the prevalence of suburbs, this seems to be the presumption reason for high housing costs). Since cars amplify use of space (parking, roads, gas stations, etc), then it follow that despite their other benefits, you would want to minimize vehicular traffic to mitigate this effect.

In other words, I think when people say things like "people should make cities that are for people" what they might be trying to imply is "people should make cities that are not for cars, because there are other things that I think should take priority".