Excellent ! This is the quality content this community needs.
Note on interest: if you use the "cash advance" feature, and withdraw cash with a credit card, interest will accrue from the first day.
On credit cards not being for everyone: I like to see it as a metaphorical Stanford marshmallow experiment. If you belong to the group who would would eat the first marshmallow right away, credit cards are not for you.
Credit cards are objectively better than debit cards if you can play the game right. They have better protection, cash back, etc... But they do have traps, and you have to be the type of person who can avoid those traps. They are designed to make you want to spend more. Examples: no interest for the first 18 months on some, cash back on most, some are even made of metal and shiny which boosts your ego when you pay at the cash register.
Also this most is mostly relevant for the US, probably Canada and a few other countries. Rules might differ elsewhere.
If you know about finance, you realize a lot of what he says is dumb. However, if you consider his audience, it makes more sense. According to the S&P Global FinLit Survey, only 57% of Americans can answer at least 3 out of 5 basic financial literacy questions (other countries range from 13% to 71%). Dave Ramsey is targeting people who are not financially literate and need very simple rules.
For example: He says to avoid debt, when we know debt can sometimes be good or bad. But for someone who doesn't grasp the concept of interest rate in the first place, the simple rule of avoiding debt works for them. It is simple.
Kinda like when you learn that the square of a number is always positive. Then you learn about 'i' in the next grade. And so forth. Dave targets the people who are still in the 1st grade of financial class, and opinions may differ but arguably he does a pretty good job if his students are learning something useful?