Such apps are not rare. In fact, some of them even make it to Ubuntu's Snap Store. This is why you should always be careful when downloading something to your system
I have a different opinion on this. I think the user should be responsible. If they allow someone to break in, it's their problem. That means users should have some technical knowledge. There's nothing wrong with antiviruses and stuff but forcing them isn't right and can turn into censorship or other unethical restrictions at some point (there already were such cases)