Even when we "copy with the keyboard and mouse", it is important to be able to look at the original address and the copied address and make sure they are identical. Malware exists that can modify the contents of your clipboard. So, it's possible that you could copy an address, then the malware modifies the contents of the clipboard to be someone else's address, and then you paste that other person's address into wherever you are using it.
There is risk from malware and people must be very carefull when copying, pasting an address in their transaction broadcasting process. Check, double check will help them to avoid risk of sending their precious bitcoins to a non-wanted address.
How to lose your Bitcoins with CTRL-C CTRL-VIt can help to reduce risk and loss of hijack from malware attackers.