Even then they weren’t ahead or winning by that much. And of the Merc wins you had the constant fight between Hamilton and Rosberg. Any given race you had 1 of 3 drivers that could win, in 2014 Ham/Ros/Ric, 2015 Ham/Ros/Vet, 2016 was pretty much Ham/Ros though.
Mercedes was from 2014 to 2016. In 2017 and 2018 the gap was smaller. 2019 it was back to before.
The only difference was that Merc had some weak tracks (Mexico at least) where RB would regularly win.
Even then they weren’t ahead or winning by that much. And of the Merc wins you had the constant fight between Hamilton and Rosberg. Any given race you had 1 of 3 drivers that could win, in 2014 Ham/Ros/Ric, 2015 Ham/Ros/Vet, 2016 was pretty much Ham/Ros though.
They weren’t that far ahead because the Mercedes was turned down to hide their true potential.