It's, per the article, not really no annual fee, you can't get the card without paying them at least $50 a year for an account with them, where the cash ends up (and then you have to figure out how to extract).
On top of that the article makes the classic mistake of saying it pays for itself if you spend $166 a month, but it only really pays for itself if the marginal value of using the card over a generic 1.5% cashback card on the things you can't get 3% for already is more than $5 a month. Things like high cashback percentages for the first $X a month in specific categories make this intentionally hard to calculate, and are part of why I never really got into optimizing my credit card benefits. It's obnoxiously hard to compare.
On top of that the article makes the classic mistake of saying it pays for itself if you spend $166 a month, but it only really pays for itself if the marginal value of using the card over a generic 1.5% cashback card on the things you can't get 3% for already is more than $5 a month. Things like high cashback percentages for the first $X a month in specific categories make this intentionally hard to calculate, and are part of why I never really got into optimizing my credit card benefits. It's obnoxiously hard to compare.