The main problem arrives when children arrive at an unfamiliar word. Whole language and reading recovery has long maintained they should use 1. Meaning/Context cues 2. Structure of sentence cues, and as a last resort 3. So-called “Visual” cues, but usually only the first letter. https://twitter.com/samjirwin/status/1258680356988829696

This is the opposite of what children should do at unknown words. Children should FIRST look at the sound letter patterns (the phoneme grapheme correspondences) and morphemes they recognise and read the word if they can, then perhaps use other clues if they need to.

With MSV you encourage guessing. For many students this can lead to constant substitution and overuse of working memory to retrieve simple or high frequency words. If they orthographically map words properly, their word recognition develops adequately and is automatic!