Formed by a suffix (-aa), whereas the second aorist is a " strong " tense, distinguished by the form of the root-syllable, we expect to find a constant tendency to diminish the number of second aorists in use.
No new second aorists, we may be sure, were formed any more than new " strong " tenses, such as came or sang, can be formed in English.
Now in Homer there are upwards of 80 second aorists (not reckoning aorists of " Verbs in µc," such as i'ar,Y, i,3rpv), whereas in all Attic prose not more than 30 are found.
In Attic poets, it is true, the number of such aorists is much larger than in prose.
Of the poetical aorists in Attic the larger part are also Homeric. Others are not really Attic at all, but borrowed from earlier Aeolic and Doric poetry.
While the whole class of " strong " aorists diminished, certain smaller groups in the class disappeared altogether.