The downsides aren’t really self-evident to me. I’ve been using credit cards for everything I can for 35 years and I can’t think of any downsides. Even the cards I’ve had that had annual fees I chose to pay that fee because the benefits were worth more than the fee to me.

I can think of plenty of times where the upsides of having a credit card were realized though.

You don't know anybody in 5-figure+ credit card debt? I know several. I don't know anybody in debit card debt.