Founders need to balance the amount of time it takes to acquire traction on the cheap, vs. via through the acceleration having a larger marketing and dev budget provides. Stagnation can kill and smaller founder equity is better than dead.
I think the overall point is not to never take outside investment, it's to carefully consider where you are in your product's lifecycle and what your market actually looks like before you take outside money. Refusing VC money if your market is huge means that someone else will take it and eat the whole market. Taking VC money when your market is small will kill your company just the same, because you won't be free to make the trade-offs necessary for a small company to succeed in a niche market.