I think this argument is similar to the argument of general privacy. Read receipts are potentially information being transmitted without your consent, though its metadata that _should_ have not direct effect on you. The same could be said for the NSA tapping your phone. They are merely observing and therefore shouldn't be affecting anything. I.E. if you aren't doing anything wrong what do you have to worry. In the same vein, if someone sees that you read something and you don't respond, if you don't believe that to be wrong, what do you have to worry. I don't fully agree with the position, but there is something to be said about feeling comfortable with your actions regardless of how others perceive them.