That is a cynical assumption. I think in most cases, people don't want eternal back-and-forth that can happen with emails when it can make sense to have a single conversation where the objections can quickly be noted/considered and the subtlety can be understood.
Of course, in some cases, this has disadvantages but like most things, we should avoid making such absolute statements and allow intelligent people to work out whether written or spoken is a better idea for each topic.
