I don’t know who Boz is, so perhaps it makes me more receptive to his message, but I agree with what he says. Steve Jobs said the exact same thing about saying no and staying on target.

I am learning the same lessons at my far smaller and less evil endeavour. There is so much good you can do, and some many low-hanging fruit, but eventually these small detours that each come with small obligations pile up and make every next move harder. There comes a point where your main task is delayed by a yak shaving expedition that started as a small favour to a single user.

I never got good at it, but I see the value in ruthless prioritisation.