The height of the letter "t" is extremely short, especially in comparison to "l" and "b". This makes it very hard to read as it affects the shape of words at a glance.
https://en.wikipedia.org/wiki/D%27Nealian
https://en.wikipedia.org/wiki/Palmer_Method
https://en.wikipedia.org/wiki/Zaner-Bloser_(teaching_script)
All have full height t, and predate computers (significantly in the case of the latter two)