While I agree with many things you said: Unfortunately, any UV light exposure is causing harm not just the exposure leading to sunburn. There is no safe level of tanning.
Use the same mental model as with X-Ray exposure.
This isn't a fair analogy since sunlight has many well documented positive effects. Vitamin D production being obvious, but also many understudied effects like nitric oxide release. It's difficult to fully root out confounding effects, but typically people with more sun exposure live for longer, despite having higher rates of skin cancer.
It's very likely the UV is an essential trigger of the benefits of sun exposure – either through supporting chemical processes like internal Vitamin-D synthesis, or simply providing the right amount of chaotic 'eustress' that exercises, without overwhelming, essential self-repair mechanisms. So, I'd strongly disagree that "any UV light exposure is causing harm".
Instead, there's a dose-response curve, as with almost everything else, and some moderate level of UV exposure is almost certainly net-beneficial.
Further, getting a light natural tan from the sun itself, without ever becoming uncomfortably burned, is probably more indicative of that optimal level of UV exposure than remaining ultra-pale from absolute avoidance of all sun-UV.
"There is no safe level of tanning" is misinformation and such confident-but-wrong statements should never be used. It's completely false to state that people shouldn't expose themselves to the sun when it's part of our biology. Overexposure and getting frequent sunburns will add up and increase chances of skin cancer, but to say that no level of sun exposure is safe is wrong.