Am I crazy for thinking there is absolutely no answer to Sombra?

On the contrary I've found a longer range / sightline character that plays either with the team or on high ground but is cognizant of the Sombra usually can pressure them, think Ashe, Widow, Pharah, Echo, most Sombra's go for the tank first and they'll operate on fairly predictable flanks, if you can anticipate them that's the biggest counter, as opposed to reacting to them, Sombra is almost a counter to reactionary play outside of OHK's. Hanzo's sonar arrow is another fantastic anticipatory tool, let's say it's attack on Hollywood, you'll shoot that on the left corner of the high ground which should temporarily zone off a Sombra from flanking the stairs, back alley or high ground. You can choose to do the same as a dueler but you'll likely get hacked which puts the onus on your own mechanical skill vs there's and you won't get the pick because of translocator, unfortunately if you force her off a flank and she teleports to the other side of the point behind her team she'll likely reenter as your tank is entering and get another hack off, assuming she hasn't put it in spawn, forcing translocator doesn't force her out of the fight for nearly long enough.

That being said, a Sombra who chooses to play rather unpredictably is going to force you to react and thus pretty much always have an advantage over your team of sorts. Outside of a Hanzo hitting a nutty 180 degree flick or your Winston / DVA / Reaper, etc being twitchy enough to hit some damage in reaction to the audio cue, she doesn't have a lot of risk.

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