Is your issue with the brainstorming quote that Marc didn't write it, or that it isn't of the quality you've come to expect from the pmarca blog? Choosing high-quality content is a valuable service. Quality and originality are orthogonal.

The brainstorming quote may not have the wow factor of some of the pmarca essays, but it's certainly relevant to people interested in startups, who spend a lot of time talking about ideas.

PG has some thought-provoking non-original content on his site too, by the way, e.g. http://www.paulgraham.com/perils.html