Likely not, but definitely depends on the situation.
And how do you know the backup is not compromised?
I think it's not as clear cut. It's always a risk assessment and depends on context.
I have to say that I'm not a security expert, just an amateur with conceptual understanding of the topic and some opinions.
Well the "sources say" implicates that they actually don't know. They've just heard someone say it. So it's definitely necessary.