Technically it made basic attacks do more damage (claw, bite, smack) against targets with SS.
I don’t think poison injectors is “considerably better” in a gameplay stand point as it stands now you don’t think about it at all. With how low the damage is and how the damage is additive, you consume the stacks without thinking or planning at all.
This already exists with Barbed Shot—Barbed Shot itself does most of what SS would do for BM, which is why I don’t really think BM or MM hunters care about the ability at all