It's easy to prove someone wrong who talks in absolutes.
I have seen 3.5s who serve an volley regularly (but it's pretty darn rare). There are absolutely 4.0 doubles players who S&V, and basically live at the net.
I have definitely seen 3.5s who serve and volley at least every once in a while (I am one).
Also, show me a powder puff 2nd serve and I'm going to be giving it a ride (or slicing it) and coming in behind it almost every time.
Also, saying all 3.5 tennis is pushing tennis is inaccurate. There are plenty of 3.5 guys who can hit the ball plenty hard, they just can't keep it in 3 times in a row.