Especially with things like cyberattacks (institution losing access to your accounts), scamming (you lose access to your accounts), power failures (everyone loses access to their accounts), etc.
I mean, I literally have a small stash of money in the closet (some 20’s and a bunch of smaller notes), so that if a semi-major disaster hits, I can still buy any supplies I can find that I need - gas, water, food, a couple nights in a hotel, whatever. Plastic is a great backup system, but it relies on me having my card, my card having enough money free, the merchant having power to run the card, the merchant’s communications working, the system they link into having power and communications, etc. With cash, it’s just “here, take this” and it’s all good.
It’s the Finding Paul Revere analysis, and it can get scary.