Look at Apple fanboys. They seem to cause haters because of their uncritical boosting of anything Apple.
(Also PG's essay seemed mostly about fanboys and haters of people, not of a particular startup)
Apple haters have a point: Apple hardware is far more expensive than similar performance on other systems. So using a traditional objective metric such as performance per dollar, Apple is objectively worse.
However, most Apple Fanboys know they are paying a premium. They love Apple for other, less quantifiable reasons, such as design quality, beautiful integration, good marketing, and the vision of making a more human machine.
The metrics that Apple fanboys value are at complete odds with many traditional computer enthusiasts, who value specs and raw performance power.
Therefore, a "fanboy" of anything (whether that's Apple, Tesla, or the startup of the day), is not necessarily being uncritical, they are just using less commonly accepted metrics of value.