Which is easy to fix.
Give Tanks 30% Resistance to the effect/duration on negative status effects, and 30% Resistance to all forms of CC including stuns, and 30% Resistance to headshots. (Then nerf down Tank survival to roughly where it is now)
And you would get a ton more Tank players in 5v5.
This was an obvious issue before 5v5 was even announced.
✅ Next Experiment: 1-2-2 SoloTank
Much less, before OW2 PVP Alpha was announced.