Let’s compare Double Shield to the 2 most pervasive meta in the history of Overwatch, Dive and GOATs.
Dive: Rarely seen in low ranks because everyone hates Winston. Also people aren’t in Voice Chat a lot. Also even if they are both of the above, GETTING 2 PEOPLE TO SIMULTANEOUSLY ATTACK A DISCORDED TARGET is unlikely, because no one does that. Bad time for immobile heroes.
GOATs: Never seen in low ranks. People in general are addicted to DPS heroes. Also most people probably didn’t even know what GOATs was because they never saw it, and don’t watch OWL. Also playing GOATs poorly is basically throwing because you don’t have burst damage or long-range damage. Bad time for DPS heroes.
Double Shield: Low Ranks like this a lot, because they use double shield a lot. High ranks use this a lot because they like to win. Bad time for DPS. Bad time for 50+% of the tank roster. Bad time for immobile supports. Unmissable damage that can’t be beaten easily because of double shield. Huge amounts of CC and AOE effects. Sniper immune.
Double Shield objectively worst meta.