Final answer:
The third reason for the poor sales of the first Remington typewriter can be inferred as perhaps due to the complex mechanics, high cost, or resistance to change from traditional handwriting to typing.
Step-by-step explanation:
The third reason the first Remington typewriter sold poorly might not be directly mentioned in the provided references, but based on historical context, we can infer several potential causes. Earlier models of typewriters, including the initial Remington, were known to have a variety of issues that affected their market performance such as being mechanically complex, prone to jamming, and having keys that struck the bottom of the paper, making it difficult for users to see what they were typing.
However, three well-known primary reasons for the poor sales of original typewriters, which can be contextualized by the information on the automation of the typesetting process, were complexity, high cost, and the initial unfamiliarity and resistance to shift from traditional penmanship to mechanized typing amongst potential consumers.