I often feel that the fingering I come up with myself as a beginner is suboptimal. What I usually do is to watch youtube videos repeatedly to study what experts do. And that really helps me correct some bad adhoc fingering. I'm sure it's an experience thing - I can totally understand why experts would consider fingering on a sheet as useless. But for beginners it can make a huge difference. You probably don't care about beginners. But that is a huge market with strong needs unsatisfied (besides auto-fingering, auto-transcription of popular songs is another one).