They will always be too slow and inconsistent no matter how they her change their AI.
Look at other close range dps heroes. They have layers of defenses, not just a bit more of HP. Invulnerabilities, sustain, in-combat mobility, hard CC, literal time rewinds, etc, a bunch of things that Sym lacks entirely to survive as a dps with no range. While some also having better long/mid range options than Sym. Oh and better burst.
There is a reason why Sym is a bad DPS hero at all levels and requires her to be a taxibot to be impactful. You remove taxibotting and all you have is a gimped Reaper.
they also put out less damage…
What are you even talking about Sym has the highest TTK of all game. Mei can oneshot Tracer with her icicle headshots. Reaper oneshots up close, DF has high dmg, Tracer has high dmg, Genji has high dmg. Even Sombra has lower TTK than Sym.
Sym’s burst is so low that Mercy’s peashooter has a lower TTK.
All close range DPS heroes in OW have much higher DPS than Sym and damage ultimates to boot.