I was looking at that recently, too, despite having a semi-auto TT myself.
There are realities about listening to music. We do fall asleep to the most relaxing stuff, or, at least, want to enjoy our reverie without moving, and yet.... tick... chik... tick... chick... that's our expensive stylus tick-chicking there!
But we also want to listen to individual tracks, or tracks out of order, and doing the business by hand is probably only easy to surgeons. This device deals with the end-of-record tick-chick, but it doesn't help with lifting and dropping the stylus at selected points.
There used to be such devices available for manual turntables, didn't there?
Except when actually lifting or dropping, it wuld not be in touch with the arm at all, so nothing would be affected.