Who should the NPS survey be sent from ?

I love the idea of making the NPS survey appear to come from the CEO or CCO. I believe the customer is more likely to respond.

Why did they rule out having it come directly from the CSM?

In my studying of best practices, it ranges from the CSM all the way to the CEO.  We currently send our heads up email that the survey is coming from our COO, and then, the survey itself comes from the CSM’s email as does the reminder email.  We use the heads up email to outline how we use the feedback and how important it is.  

For our NPS and CSAT surveys, we made an email alias for Customer Experience so email responses/OOO messages go to an inbox managed by CXOps.  In each survey email, the signature comes from the VP of CX.

Also be sure to make your subject line something that will make sense to the customer if you decide to use an email alias - we had to change ours after we had some responses come back that said they didn’t understand what/who they were rating. 

My general finding is that customers are more prone to read and respond to emails that are sent by people they know. That's why we are sending messages from our CSM's consistently. However, if you have a CS model in which strategic customer stakeholders have a regular touchpoint with a CEO, regional head or other roles in your company and you are surveying those stakeholders, it makes sense to send from that role. If this would be the only time they hear from your CEO or regional head, I don't think it it the right choice to send it from these roles.

One reason many organizations don’t like to send it from the CSM is because they are less likely to get a true response because the respondent is more cautious in their response if they are having a bad engagement.

I agree that a user is more likely to respond if it comes from a name than a distro list. 

I like to see it come from the CEO for strategic accounts and the CCO for all other accounts. Then follow ups come directly from the CSM. They can be semi-automated (automated for promoters, CTAs for passives and detractors). 

I agree with Jef, we also send it from CSM.