The lazy approach of just lowering the HP of tanks in OQ and arcade is a poor-man’s solution. Now you play games where Hanzo, Sojourn, Widow, Reaper and other tank-busters just destroy the tanks. Their HP is lowered, but high burst damage is still the same. If you end up being the only tank on a team you get destroyed by a single high-burst hero.
More thought should be put into how to balance the tanks in other modes in a better way. Too many of the games are just unplayable. Hanzo and Widow are the biggest problems as they eat a tank’s HP in 1s flat.
A better starting point would be to limit each team to 2 tanks and go from there.