Fall damage existed in Overwatch and almost made it to the final release of the game, but a few characters prevented the mechanic from working.
Jeff Kaplan, Game Director of Overwatch, explained that everyone’s favorite sniper Widowmaker was actually a main reason why fall damage did not make it to the final product.
“With Widowmaker, it felt strange and unintuitive to be able to grapple to high places but not be able to jump down without taking damage.” said Kaplan. “We found ourselves grappling back down to lower points, which was awkward.”
Other characters that presented a fall damage problem were Pharah and Reaper, both of which can reach heights like Widow.
“Pharah was really odd. If you didn’t feather your jets right before touching the ground you would splat’” he explained. :And with Reaper, we kept teleporting to high locations with no ability to get safely down.”
At first, the Overwatch team decided to exempt those three characters from fall damage but kept the mechanic in the game. Eventually, they had a hard time deciding who should be penalized by falling and who shouldn’t.
D.Va’s flying mech, Hanzo’s wall climbing and Genji’s double jump were presumably other characters who puzzled the fall damage decision makers.
“It felt arbitrary who would take fall damage and who was immune so we removed the mechanic completely,” said Kaplan.
A character like Pharah being able to fly but not land would certainly be an awkward mechanic and Overwatch might be a completely different game with fall damage around.
Source: Blizzard Forums