Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Why is the dominant investing advice for individuals to use mutual funds, exchanged traded funds (ETFs), etc
Cost.  If an investor wanted to diversify his portfolio by investing in the companies that make up the S&P 500, the per-share and commission costs to individually place trades for each and every one of those companies would be prohibitive. I can buy one share of an exchange-traded fund that tracks the S&P 500 for less than the purchase price of a single share in some of the companies that make up the index.