alt Hacker News> So your solution is to ban the sale of any kind of knife.
If you give a toddler a butcher's knife to play with and they get hurt, you'll likely get in trouble for child endangerment.
Using my car requires it be registered, pass my state's safety standards, and that I possess a valid license and follow a wide variety of rules.
Maybe a certain level of protection is, at times, acceptable?
Those are very different scenarios because your "protection" is the threat of consequences. You can freely buy and use knives, you can drive your own car, but you can only use your phone to do what Apple approves of? Sure, banning knives, replacing cars with public transport, and locking down all computers should be safer in theory... but murderers will still murder and scammers will still scam.
Social engineering is the weakest link even if your grandma is doing all her banking on Windows XP.