Roadhog is countered by reaper, mei, phara (unless she flies low), doom, ana, brig, mcree, sombra and probably some other characters i’m forgetting about.
Hanzo, while annoying can be dived by doom, genji, winston, dva, ball etc.
What do you do against mei? Her heal cleanses all effects and doesn’t have a cast time, her wall also doesn’t have a cast time, she gets her ult in 2.3 nanoseconds. Need I go on? I guess if you run mcree, brig, rein, zarya or something like that you’d have a chance but mei counters so many characters while having very few hard counters herself.