Okay yes sometimes it's the developer lol.

I guess my point is that the software dev process is a team effort and preventing copy paste is not normally done "just for funsies", or intentionally to frustrate the user, or because it's standard developer practice - there's normally a motivating cause, and it just so happens that the developer in this case happens to be the same person who has to do support for end users, and that's where the requirement had come from.

The reason preventing copy-paste is a go-to-hell crime (even if there are reasons) is because there are much better ways for a business to solve whatever problem motivated them disabling it. In this example for instance, send an email the user can click that proves ownership. Much less user-hostile than having them type it twice without copy-paste.