If the VC firm is taking 15% of your company for $15m, then you've got a valuation of $100m. As far as I know, the "We all know that nine out of ten startups fail" applies to all startups, not the ones that are being valued at $100m. Also, I think very few VCs are investing $15m into a company that they expect to have a 90% chance of failure. You're looking at more of a 3-5x on some of the deals to carry the consistent 1-2x that the rest of the portfolio is returning.
I don't disagree with a lot of the points in the article, but saying that a VC firm with a $150m fund is betting the farm on one $15m investment exiting at $3bn should raise some eyebrows.