Nah, they are, and I hate those characters with intensity. They require no skill and have way too many options and diverse abilities that make them so unbalanced.
Mei has long range ice spikes, freezing (which only takes like 2-3 seconds), healing, ice wall, and headshot damage.
Junkrat has long range attacks (short range explosions don't damage him), explosives, an ult that requires no risk, grenades upon death that are unnecessarily damaging and hard to avoid and annoying ass traps.
Compare that to the rest of the roster and everyone else comes up short. Mei and Junkrat are THE worst.