Also I think that different organizations have different thresholds for how much they can tolerate with an underperforming employee. In larger organizations, I have seen situations where an employee was not a great fit for the role they were originally hired for, but over time were able to move into a different role where they were effective. E.g. someone who can't write code to save their life, but is actually quite effective as a middle manager.

But in a startup situation where every new hire is going to make a huge impact on the team, and "money is running out" (as the article is titled), you might necessarily need to be less forgiving.