Yet they only started winning after Hamilton joined. Before 2014, Mercedes had zero constructor’s championships. Mercedes engines had won the championship only twice in F1’s history. There was no guarantee they would win championships. Renault engines, which powered Red Bull, had a more successful history. From 2010 to 2013, Red Bull had the best car, which enabled Vettel to win 4 straight championships. I don’t hear people whining about it being “the car rather than the driver”. Even with the best car, Lewis pushes it to the limit, and has an incredible team helping him.
In fact, people like Schumacher and Hamilton, who have proved that they can win with more than one team, are true legends. The same goes for Valentino Rossi in MotoGP. He won titles with both Honda and Yamaha.
In 2014 there were engine changes which was the begining if the turbo hybrid era in which mercedes became dominant. Redbull was dominant from 2010 which was the aero era. 2021 engine regulations might see emergence of a team like renault being dominant so coping up with these regulations plays a major role.