Isn't that just a suggestion to get up and running quickly (for example on a dev VM)? There's nobody forcing devs to blindly follow the instruction and pipe it directly into bash. You are free to curl -L -o install.sh get.whatever.com if you want to inspect the install script.
It's not an argument at all. It's a manner of speech. To be more verbose: I can't think of a compelling reason why you would blindly type whatever instructions you see on the screen, into your terminal. Unless you were being forced.
