They're being downvoted for making unsubstantiated claims about security vulnerabilities, and for not understanding the benefits of avoiding copy+pasting.
> And as you say it doesn't even really offer any benefit over cutting and pasting from the CLI.
It saves you from the fact that every application on your system, and some browser extensions can read your clipboard silently with no way for you to know. It saves you from phishing attacks from gіthub.com (note the i is a cyrillic i), it saves you from misconfigured permissions on your ssh folder, and from any "nosey" pip/npm install scripts that you might run on your development machine. It also means you don't lose your ssh keys in the case of data failure.