Marfa is the same population as advised in this article but it's ten times larger.
There are plenty of recent examples of development on the scale that this article suggests. The area just to the west of Warm Springs BART station in Fremont, California is 90 acres. The New Urbanist polestar of Hercules, California is about 150 acres.
It's true that it's legal geographic size is ~1.5 square miles. However if you look at Google Maps a good 30% of it is just empty/undeveloped land previously (still?) owned by the military.
So yes, it's still bigger geographically, but it still only takes 15-20 minutes to walk from one end to the other; I've visited a few times. I'm not very familiar with either location you mentioned, but I would say for Marfa to be 3 hours away from the next-largest town (El Paso), have no commercial airport or passenger train line, and still be a self-sustaining walkable town is impressive.
I'm possibly mistaken, but the first example you pointed out looks to be an apartment complex next to a train station within a larger city and Hercules, CA is a 20 square mile (maybe I'm looking at the wrong city?) suburb of SF; I don't think those are examples of what this article is saying?
The New Urbanist part of Hercules is very small and easy to overlook. It does not hit every point that the article mentions, but it is an example of some of them.
There are plenty of recent examples of development on the scale that this article suggests. The area just to the west of Warm Springs BART station in Fremont, California is 90 acres. The New Urbanist polestar of Hercules, California is about 150 acres.