What is the purpose of the Penitential Rite in a Catholic Mass?

The Mass in the Roman Catholic Church includes a [Penitential Rite](https://en.wikipedia.org/wiki/Penitential_Rite) , where a Penitential Act is effected. However, as the [Roman Misal](https://www.dropbox.com/s/en6h3a7awzq47dh/THE%20ROMAN%20MISSAL.pdf?dl=0) states (page 55): >51. After this, the Priest calls upon the whole community to take part in the Penitential Act, which, after a brief pause for silence, it does by means of a formula of general confession. The rite concludes with the Priest’s absolution, which, however, **lacks the efficacy of the Sacrament of Penance.** This is, such act **is not equivalent** to the Sacrament of Confession. As [this other](https://en.wikipedia.org/wiki/Mass_in_the_Catholic_Church#Ritual_Masses) entry in Wikipedia about the mass states, >Confession (Penance or Reconciliation) is the only sacrament not celebrated within a Eucharistic framework and for which therefore no Ritual Mass is provided. I wonder then, which is the purpose of such penitential act? Is there somewhere an "official" or authoritative analysis of this? Maybe by a Church Father?