This is probably due to the fact that when we usually read, we just perform some kind of "pattern recognition" without even thinking about it: we just look at the first letters and the last ones, and our brain makes up the word as we read it [0].

Probably this font forces us to read letter by letter, and this is what makes it easier for dyslexic people to read the text (they don't get confused too much of the next / previous characters), and so difficult for people who aren't used to read letter by letter.

Interesting :)

[0]: https://en.m.wikipedia.org/wiki/Typoglycemia