4dps is ok. 4dps 2 tanks is kinda harsh, but 4dps 1 tank 1heal or 4 dps 2 heal is something that is easily winnable. No heals is what is nearly impossible to win. If you have 4dps 2tanks I would even go for 5dps and hog. Take dps that has good survivability like soldier, tarcer, sombra, widow etc. depeding on map ofc, but sombra is quite vital.
Meta is to blame to be honest. The way to win is very clear - grav+dragon combo with a shield and a strong healer. If your team is playing against this and doesn’t run the same comp you are screwed.