The article and none of the comments mention rewards yet, which are the biggest reason to use cards! Credit card processors charge large fees on transactions, which is a huge tax on just about... everything. You can make a lot of that tax back via rewards. And not every card user has a good rewards-paying card - it's usually the more rich that do - so rewards function as a wealth transfer from the less rich to the mo…
Various studies have shown that, for the investment needed to "maximise your rewards" (ie time needed to research the different cards on the market / read the fine print of your chosen product / put through payments on a high rewards card; money on signup fees, recurring fees, transaction fees, etc), you'll achieve a much better ROI just investing the equivalent time and money into an index fund.
Still wouldn’t recommend them for anyone who’s not particularly good with money, but 2% back for almost no effort is a pretty good trade-off. Keeping track of rotating quarterly bonuses? Yeah—-then it’s worth thinking about ROI of your time.