I went to Financial Planning school to become a CFP... 3 hours/day, 5 days a week for 2 years. I could have skipped all that and just read your paragraph above.
On the dave Ramsey thread on Reddit they have modified the program. Skip mutual funds and do index ETFs to save the fees. How big is Dave Ramsey in the US? I only found him on YouTube as I live in London.
Ramsey is a fairly big fish in a small pond. His advice is basically good to follow. If ETFs had come along first, there likely would have never been a mutual fund industry. The first mutual fund was begun in 1924.