You can say what you want, Nick has produced 10 world #1s. How many have serve and volley coaches produced?
Serve and volleyers like Dent and Rampras have not achieved much. Today, even the Doctor with his serve and physical attributes cannot win with S&V. The top four players today are baseliners.
If you just want to criticize someone for the sake of it, go ahead. But it is clear that only those who can construct points and grind it can win today, and for that clay training is very beneficial.
If someone like Sampras shows up again, that is good. Otherwise, today's game requires stamina, mental strength and patience. The Donald or Vania King are not going to be great players whether they serve and volley or not. That is not the issue.