Perhaps the definition needs to change?
Note the above is from the article which is focused on the UK. It could be different in other countries.
A person with IQ 100 (or whatever the mean IQ is) learning to read slower than average is different than a person with IQ 60 learning to read slower than average. You cannot completely remove the IQ component.
If say dyslexia behind the scenes looked something like the difference between being left handed or right handed, a persons natural athletic skill (IQ) might improve their odds of throwing a good right handed pass yet regardless of athletic skill their outcomes would be better throwing left handed.