I'm white enough that 5 mins of near midday sun gives me sunburns. In summer spf >30 is a must. Even day to day some sunscreen on my face and neck is a must.
Probably says a lot about where people live. The OP’s advice is a recipe for still getting skin cancer here (we get a max UV index at or over 11 every day for months where I live) - sunscreen is unavoidable to stay safe for a lot of the country because even little bits of incidental exposure add up. Whereas if you’re in the northern parts of US/Europe it’s probably OK.
"it's only sunburn that's dangerous" stopped being the advice years ago, probably because people (younger dumb me included) were like "I only get sunburn once a year and after that I don't need sunscreen!"
Skin damage from UV is cumulative. How careful you have to be depends on your skin type but the general advice is that sun protection should be worn when the UV index is over 3, or if you're spending any extended time in the sun.