In reality things are complicated and one principle[1] cannot account for all situations, so we deal with things differently as they come up. Murder happens to be an extremely old problem; public health is also, but knowledge of microbes and infection mechanisms are brand new, so we are still figuring it out.
[1] "personal responsibility" makes little sense as a moral catch-all when ignoring your own health can cause other people problems
- ...ignoring your own health can cause other people problems"
How much of Netflix cause health problem for you? What about food? How much of junk food are you eating? Or maybe we should ban tabaco and alcohol. Or profesional sport. All of that is potential threat for your health. Being overprotective could damage your mental health... etc.
Your comparisons between issues in modern cultural and political concepts are fascinating. Please tell me how overeating, obesity, personal addictions, competitive athletics and media consumption are related to microbial infection vectors so that I can write a definitive thesis about externalities and how they don't exist because I want to live in a libertarian fantasy world.
I will make a comparison, tell me how you find it: "Dumping waste into the river shouldn't be illegal because you dump your waste in your toilet every day and it goes to the river."
Does it sound reasonable? Sure. But I haven't defined scope and I haven't defined effect and I haven't even defined what 'waste' is; I just made up two scenarios which could have similar outcomes and then called it day -- but if you actually care about what happens to the world you need to get a little more detailed than writing silly grandiose political statements and making non-sensical metaphors comparing indicting someone for murder with crafting public health policy.
[1] "personal responsibility" makes little sense as a moral catch-all when ignoring your own health can cause other people problems