Question what? People actually enjoyed that game and just because it wasnt your cup of tea, that dont mean there is a conspiracy.
If we look at the consensus of sites that chose Death Stranding as their game of the year.
2019
Death Stranding - 118 GOTY awards
Resident Evil 2 Remake - 94 GOTY awards
Seikiro - 85 GOTY awards
Control - 36 GOTY awards
Star Wars Jedi: Fallen Order - 22 GOTY awards
As you can see multiple outlets enjoyed the game and named it their game of the year. There is no questions needed because there's not conspiracies.
Your beloved Luigi's Mansion on got only 1 GOTY award that year so you bringing up it sold more than Death Stranding so it deserved it more dont hold any weight because the gaming outlet majority thought otherwise.
Source:
GOTY 2019