how alone expresses manner
I like how you say those words, "tins of tuna".
or a way of being
You will never fully appreciate how things were during the war.
how + modifier expresses degree:
It is not known at this time how badly the car was damaged.
How alone can be used as a comparand with a phrase that also expresses manner:
Her pronunciation of that word is clearer than how you say it.
Simpler would be "Her pronunciation of that word is clearer than yours". Things can stray into marginal territory when a simple parallel pronoun is avoided and a noun is compared with how.
Life now is much better than how it was during the war.marginal
Life now is much better than it was during the war.
It is possible to compare the degree of one thing to the degree of another, so that how + modifier can be used in a comparison with another how + modifier. The words of comparison will not be a simple comparative but will create a new predicate:
How poorly she sings is nothing compared to how badly you cook.
How stubborn she is is less troubling to us than how lazy you are.
How poorly she sings is less a problem than how poorly you sing (because she dances very well and you can't dance at all.)