CTRL+C/CTRL+V isn't foolproof either
"How to fix the fat-fingered problem? Well – and it seems almost incomprehensible that the body had to dedicate an entire chapter to pointing this out – give people the power of CTRL+C/CTRL+V"
I've noticed when copying and pasting IP addresses out of logs, it's just too easy to miss out the first or last digits from an IP address.
There's also the problem of getting the correct line when doing it visually.
It's far better to write a script to ensure accuracy.