This IS the descriptive approach. Trying to wrangle fish out of ghoti is simply not how people read.

Reminder that according to the actual rules of English orthography, “ghoti” can never be pronounced as “fish”, because said rules feature “position within a word/syllable” very prominently. An onset g simply can’t be pronounced the same way as a final gh, and in fact, any “gh” followed immediately by a vowel must be pronounced with the hard /g/ sound. “ti” is only ever allowed to fricitize to the “sh” sound if it’s followed by another vowel. Ghoti can only be pronounced the same as “goatee”, and English speakers know this intuitively even if they can’t articulate why they know this, the same as we internalize hundreds of other language rules without knowing that we know them.