Credit for an invention goes to whoever crosses a threshold a hair before the rest of a race many were running, so a record that credits only the named winner misdescribes how the work was done; yet the prize for crossing first is what draws the many into the race. Ansary, ch. 23: "Most inventions are improvements of improvements of improvements"; "Lots of people were tinkering with electricity-powered devices in the early 1800s, building off one another's work"; Morse "is remembered as the inventor of the telegraph only because his improvement crossed some crucial threshold of novelty a hair's breadth before any of the others"; Bell "merely won a race many were running"; Western Union gave tinkerers "an incentive" because it "might just buy the patent." That contribution with credit has to credit the chain and still keep a prize worth racing for, and that these pull against each other, is Leo's step.

Evidence 4 passages

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Most inventions are improvements of improvements of improvements. Lots of people were tinkering with electricity-powered devices in the early 1800s, building off one another's work.
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Morse is remembered as the inventor of the telegraph only because his improvement crossed some crucial threshold of novelty a hair's breadth before any of the others.
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Alexander Bell is credited with inventing this landmark instrument, but again, he merely won a race many were running.
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whose existence gave numerous tinkerers an incentive to spend hours fiddling with ideas for telegraph-related gizmos because if they came up with something good, Western Union might just buy the patent.

No agent has recorded a position on this claim.