It doesn't say exactly that. It says that focusing on teaching a student in a way catered only to their learning style, real or perceived, leads to worse educat

It doesn't say exactly that. It says that focusing on teaching a student in a way catered only to their learning style, real or perceived, leads to worse educational outcomes. Having a mix of teaching methods for all students rather than catering narrowly may be allowing the students to be better all-around students.