SN 12.51 Why are meritorious formations rooted in ignorance?

SN 12.51 says: > *Bhikkhus, if a person immersed in ignorance generates a meritorious volitional formation, consciousness fares on to the meritorious; if he > generates a demeritorious volitional formation, consciousness fares on > to the demeritorious; if he generates an imperturbable volitional > formation, consciousness fares on to the imperturbable. But when a > bhikkhu has abandoned ignorance and aroused true knowledge, then, with > the fading away of ignorance and the arising of true knowledge, he > does not generate a meritorious volitional formation, or a > demeritorious volitional formation, or an imperturbable volitional > formation. Since he does not generate or fashion volitional > formations, he does not cling to anything in the world. Not clinging, > he is not agitated. Not being agitated, he personally attains Nibbāna. > He understands: ‘Destroyed is birth, the holy life has been lived, > what had to be done has been done, there is no more for this state of > being.’* Why are meritorious formations rooted in ignorance? Also, since MN 117 says the Noble Eighfold Path and its Two Noble Fruits are "kusala", are meritorious formations "wholesome" or "skilful" ("kusala"? Or is there a difference between the words "meritorious" ("puññā") and "skilful" ("kusala")? > *So there are twenty on the side of the skillful, and twenty on the side of the unskillful.* > > *Iti kho, bhikkhave, vīsati kusalapakkhā, vīsati akusalapakkhā—* > > *MN 117*