From what I can tell, the author is incorrect about the example given in "Optimizer gremlins". I tested an example on my own data and micro-partition pruning was active.

The issue with dbt models in Snowflake is that if you ever perform a full-refresh and don't sort it, you ruin any natural clustering that arises from an incremental model. I've run into this issue many times. Auto-clustering gets too expensive at scale and Snowflake doesn't give you much guidance on alternatives.