That is a really bad example, because English does have fairly productive pronunciation rules [1], and trying to make 'fish' come out of ghoti requires breaking them. 'gh' only occurs as an /f/ sound when it occurs at the end of a syllable; as an initial consonant cluster, it's invariably /g/. Turning 'ti' to /ʃ/ is a fairly normal affricatization, which requires a subsequent vowel, which is lacking here (consider words like 'ratio', 'gracious', or 'nation'). Even turning the 'o' into /ɪ/ relies on fairly regular vowel destressing, which there's no reason to expect in 'ghoti'--which should be pronounced per English rules, pretty unambiguously, like goatee.
There are some real issues with English spelling, like the inconsistency of pronouncing 'ea' as /i/ or /ɛ/ (consider, uh, read and read). But 'ghoti' isn't one of them, because that's a case where there's not a lot of ambiguity in English pronunciation.
[1] The worst offenders in English pronunciation are when English borrows foreign words both with foreign pronunciations and foreign spellings.
There are some real issues with English spelling, like the inconsistency of pronouncing 'ea' as /i/ or /ɛ/ (consider, uh, read and read). But 'ghoti' isn't one of them, because that's a case where there's not a lot of ambiguity in English pronunciation.
[1] The worst offenders in English pronunciation are when English borrows foreign words both with foreign pronunciations and foreign spellings.