Mercedes are in luck. The heat of 37 and 38 degrees is coming over the next days, just too soon. In the weekend it is back to normal summer values, in which they did fine at Paul Ricard.
Best WDC-drivers in F1 history:
Schumacher, Senna, Fangio
Driving a dominant car in the most dominant team ever, helped by favorable rule changes, against subtop teammates does not make you the GOAT (but still superb). It just helps you inflate/skew your stats.