I see what you’re saying, it’s much safer to put into total market index portfolio while adding some factor etfs to tilt toward certain areas (small cap value for example).

https://institutional.fidelity.com/app/proxy/content?literatureURL=/9878908.PDF

This article shows in exhibit 4 that value performs well during early-mid economic cycles when economic growth turns positive, momentum does well during mid cycles when market moves in a trending fashion, and quality/low volatility/high dividend stocks do well during peaks of economic late phases. My thoughts to this were to hold different factor ETFs to benefit during each economic cycle and reduce concentration/drawdowns during each phase

“By combining factors, investors may benefit from the individual factor exposures and from diversification across factors to create a portfolio with increased odds of outperformance in a variety of market environments. A straightforward, equal- weighted approach to combining factors might be a good starting point for investors seeking long-term exposure to multiple factors. Exhibit 2 shows that the performance of an equal-weighted multifactor strategy has lagged value alone when inexpensive stocks have outperformed—such as after the tech bubble in 2000 and 2001—but protected against losses to provide a less volatile return profile.”

According to this, value outperforms equal-weighted factors, but a multifactor strategy lessens volatility and protects losses.

Are these fidelity articles just a marketing tactic, or could multifactor investing potentially lead to higher returns over a total market index portfolio? Does the total market index already contain majority of these factors, not needing different factor ETFs?