I've used PostGIS a few times before and I'm curious why you wouldn't want to use it? It's very straightforward to install and use.

I also feel like it makes your Schema and database setup more easily extensible than if you start with the minimum and have to change it all later.

I'd agree with this, there's so little overhead with using it.

One other positive side effect is that you can plug QGIS or similar straight in and visualise your data with minimal effort.

So... You probably need PostGIS if you’re writing a GIS/NIS style application or do analysis but not to show a few map pins on Google Maps.

I personally like it and don’t even feel like it’s very “heavy” like the article implies. Great performance even when running locally on my laptop in my dev environment and with tens of thousands of objects in the topology. :)

I am reading it correctly that the article is suggesting to install the earthdistance extension instead of PostGIS when needing distances between points. Why not go for PostGIS instead then?

Because then you can't do lazy content marketing on your blog.