So that you don't accidentally run malware. MacOS is not iOS, you can run unsigned code if you really want to, but it will make you jump through a few hoops.
How is this better than trying to eliminate the problem between the keyboard and the computer? The user won't learn if the computer handholds them through everything.
How is this better than trying to eliminate the problem between the keyboard and the computer? The user won't learn if the computer handholds them through everything.