I mean or you could just avoid the 5m space around sym. Just take her out from a distance. And if you were a decent shot you could also outdamage her. She had a time to kill of over 2 seconds
Mei would be a really good option if you struggle with lock on you can freeze her and keep her from ramping up
It had a ton of disadvantages that made lock on justifiable. The real issues of sym was her shield gen that needed a nerf to duration. That would keep sym from snowballing and in turn help out everyone vs sym. While also keeping her in a viable spot