Good for you. As you suggested, Ramsey is personal finance 101. His advice is great for people flirting with financial disaster and trying to work toward stability, but I doubt anyone can become really wealthy using his system. I used to work with high-net worth real estate investors ($50M-$100M portfolios). Every one used leverage to help build their portfolio. They started out highly levered and, once they experienced economic cycles, saw the light on low/moderate leverage (30-60% LTV). Debt was an important tool as they could buy 3-4x as many properties with debt than with straight equity. I truly believe none would have been able to achieve the results they did if they were Dave Ramsey acolytes.
On the margin, FICO scores can impact your ability to get credit, the amount of the credit, the terms of the credit, and the pricing of that credit. DR followers shouldn't care, but for those of us who may want to borrow for an opportunity that may arise, it makes sense to be somewhat mindful of it. Past a point, it is just a number used in a @!&% measuring contest.
He wouldn't claim people can become massively wealthy with his system. That's unless they have a massive income. It takes high levels of risk to become massively wealthy. We can all agree there. I also follow Robert Kiyosaki and Grant Cardone closely and they're always saying you need to take risk to build 7-figure+ wealth. Dave's whole thing is low to no risk; slow and steady WILL win the race and will put you well above average net worth. Anyone that followed Dave's stuff to the nail starting before the age of 30 with an average income would retire with several million dollars and not a single payment to the bank (unless our markets completely collapsed; that's based on average return since market inception). He has the data in a comprehensive white paper on his website to prove it. And a massive pile of testimonials from low income earners that are millionaires because of following his principles. The book
Everyday Millionaires is a short read and summarizes all the data if you got an open mind. That's all the average person wants. Owning rental property and becoming massively wealthy is not even a thought to the average household. It's simply paying the bills they're drowning in.
I'd argue his advice is for the average American and not a small cohort of out-of-control people everyone claims it's for. The average American household income is $85K before taxes. The average credit card debt per household is $6K. Average mortgage payment is $1,500. Average car payment is $650 x 2 per household. Average household student loan debt is $30K. I'm sure I'm missing other big debts the average household has (ATV, boat, camper, motorcycle, etc). Add in the eating out, recreation, vacation, and entertainment most households have and the math doesn't really add up that the average American household is in happy land. And that's shown by our divorce rate. (now is a good time to point out, the average household cannot responsibly use credit cards as the data above shows. They're losing their ass on interest chasing points and cash back)
I used Dave to set my family in a position to invest. If we had the average car payment, student loan payment, and whatever else; the investing in real estate conversation wouldn't even be a possibility at our table. As is the case with most Americans. No one is arguing with you that the extremely wealthy are highly leveraged. Me, you, and Dave all agree on that. For every one of them highly leveraged $50-$100M guys, there are five that are busted broke. For me, it's all about finding the sweet spot between that and Dave. And it takes an extremely disciplined person. Those disciplines were instilled in me through Dave. That is all and I'm grateful for it. Several have that discipline without his advice. Good for them, but that's far from average. I'm willing to take on some of the risk to build wealth outside of what he teachers, but I have the fallbacks in place if it fails. Most people are not like that. Dave was one of the people that didn't have the fallbacks and that's why he went bankrupt.
Going back to the average American household number above, there's no banker in their right mind that would give that person a highly leveraged real estate loan based on their debt to income ratio. They wouldn't even get to the part of the conversation when the credit score is looked at. I have no idea what my credit score was when I bought my house. But we were not pre-approved when we put in our offer. When we called the bank and told them our income with no debt and what we wanted to borrow, they simply laughed and told us to put in the offer. We could've essentially had a credit score of 0.
edit to add: there was a guy on here a few years ago in a similar thread claiming how stupid people were for paying off debt when buying debt is so cheap and the market is red hot. I can't imagine the situation he's in today.