This is the true sign of a programmer's transcendence. Specifically the irrational joy of seeing net negative LOC diffs.
It's not about how much you can add. It's about how much you can remove without sacrificing correctness, functionality, and readability.
Deleted code on the other hand, is never a liability. The act of deleting it may be, but due diligence should ensure it is not.
Once I was using an industrial camera that had a mode that allowed it to mirror or “flip” the image output. Unfortunately, after running for a few hours, sometimes it would decide to flip the image on its own. Had that “flip” feature not existed, the bug could never have occurred.
The point isn’t that you shouldn’t add useful features, but that even easy to add features aren’t as “free” as they might seem and the risk of adding them should be recognized and weighed against their utility.
He would write helper functions that he thought would be useful before writing actual code and often ended up wasting time. Half the functions he wrote, he never actually used, but he'd still spend time writing them and unit tests for them.