Yes, I understand that, but how do I _know_ if I am using this functionality? In this case, it is the ability for an app to install and execute arbitrary code

Yes, I understand that, but how do I _know_ if I am using this functionality? In this case, it is the ability for an app to install and execute arbitrary code that hasn't been reviewed. I download an update to DoodleJump and it installs some malware on my device. I'd be none the wiser. I don't want that stress, which is why I chose an Apple device. It protects me from that scenario.