Guys, I get there's an important agenda at stake here, but this is common sense and basic tennis knowledge. OF COURSE it is easier to return serves when the ball doesn't stay too low. This applies to literally every tennis player in history, including the GOAT, Roger Federer.
Interestingly, here are Roger's comments on Halle vs. Stuttgart from last year:
“This is an easier court to play than last week in Stuttgart,”
“The ball bounces up higher into my strike zone. I was connecting well on returns and I could read his serve."
https://www.express.co.uk/sport/tennis/977270/Roger-Federer-Halle-Stuttgart-grass-court
Now please can you guys for once try to be objective and logical when it comes to this topic? Yes, Roger 10000% benefited from the slowing down of Wimbledon in terms of being able to play his all around game while dominating from the baseline, as it increased the margins, relatively neutralized serves against big servers, allowed him to return far more comfortably, and basically meant that whoever plays better from the baseline has a very good chance of winning. Needless to say, Roger was the best baseliner of his generation.
Now, this DOES NOT mean that he wouldn't have done extremely well on the old grass too, and he certainly would have preferred that grass vs. the likes of Nadal and Djokovic, but yes, there's literally no way to deny it, he benefited from slower grass conditions as he perfectly combined his attacking baseline game with his all around game. The results from his prime years speak from themselves, and he didn't need to make huge adjustments when playing on grass so the transition from and to other surfaces was easier, the same way it was for everyone else.
Roger being comfortable playing serve and volley tennis does not negate that. He sure was comfortable, but not nearly as comfortable as playing his natural offensive baseline game and combining it with coming to the net.