Not so far as to say characters like Moira/Mei won't be able to damage robotic characters but enough to make the fights and team compositions more dynamic and skillful if you choose to play smart. Examples:

• slightly buffing Illari in sunlit areas and nerfing her in shady areas
• torb healing robotic characters with his hammer
• JQ not being able to bleed omnics
• Fortify not being immune to the physical aspects of abilities like gravitic flux and charge
• the ability to wraith and blink out of junk traps/pulse bombs/mag grenades again
• Mei primary and ult extinguishing both teammates and enemies burned by Mauga/Ashe
• Mei primary and ult nullifying torb ult
• Make ice block breakable
• Zarya ult instantly kills or takes 50% health at least
• Wrecking Ball gets the Dva second life
• No matter the map make Pharahs have to go to the Route 66 gas station to refill their jetfuel
• Illari's healing gives enemies cancer