[cjs_ac]

Irregular verbs (go/went, and so on) congugate (change according to tense and subject) using rules just like regular verbs, except that they have different rules. The irregular verbs use Germanic conjugations (cf. man/men, child/children) whereas the regular verbs use grammatical constructions from other source languages.

[abeppu]

In every language, for every word, there will be some history and source. And one can always declare a "different rule" around exceptional cases ... but that's kind of vacuous, and speakers have to remember which words are subject to a minority "rule", so claiming they aren't "exceptions" seems disingenuous.

But if you look at the words in English for which we have "different rules", and you look at which words in other languages which have "different rules" ... they typically line up with frequency. You'll note that the small list of verbs listed above also happen to be irregular verbs in a lot of languages.

[int_19h]

That assertion about frequency really needs some data to support it, because the only example I can think of that is very common in that regard is the word "to be", which is special in many ways other than its frequency.