I save values that I want to be able to copy and paste for repeated use (example commands I need to enter at a command prompt for tasks that I only do occasionally). Sometimes I'll accidentally cut rather than copy. Once I've grabbed the value, I don't have a reason to return to the note, so it won't be until the next time that I want to copy the value that I'll realize I cut it the last time. By then, I usually can't remember what the value was.
My workaround is to copy the note and label it 'backup'. Of course, if I edit the note, I have to remember to copy the edits to the backup, which is definitely a potential point of failure.
I'd much prefer to be able to change a note to read-only, realizing that I'd have to change it back if I want to edit the note.