In the part where the claim is made that individual characters matter there's a footnote link that ultimately goes to this PDF thesis[1].
That thesis has a claim itself:
> Creating a well designed, legible typeface is therefore not about creating dissimilar characters; the aim must be to find, amongst other things,
an optimal balance between uniformity and differentiation and,
through that, to attain legibility
At the end of the related chapter, where the author surveys some studies about letter and word recognition. It seems like the distinctions made in this font may be informed by that kind of perspective - not that increased differentiation of characters is good on its own.
This is just at a glance but it seems there is at least a thread there to follow about evidence and reasoning.
That thesis has a claim itself:
> Creating a well designed, legible typeface is therefore not about creating dissimilar characters; the aim must be to find, amongst other things, an optimal balance between uniformity and differentiation and, through that, to attain legibility
At the end of the related chapter, where the author surveys some studies about letter and word recognition. It seems like the distinctions made in this font may be informed by that kind of perspective - not that increased differentiation of characters is good on its own.
This is just at a glance but it seems there is at least a thread there to follow about evidence and reasoning.
[1] https://core.ac.uk/download/pdf/40037679.pdf