Okay, I’m back.
The RCIA is the ordinary means of Conversion in the post-Christian era, and is modeled after the process that was used during the pre-Christian era, when the Apostles and the first generations of Christians were first coming into the Church as un-catechized adults.
During the Christian era, this process was unnecessary, because the vast majority of adults were catechized during childhood. Those few adults who came to the Church for Catechesis as adults could be brought into the Church one at a time, because they were few and far between. Since the culture itself was Christian, it was possible for a person to receive a few lessons from the priest, be baptized and receive First Holy Communion when deemed ready by the instructing priest, and then receive Confirmation at the next visit of the Bishop to that parish. It was assumed that the adult thus catechized would integrate into the parish community and take up his place in the social order of the parish, since the whole of society expected him to do so. He didn’t need to be prodded to attend Sunday Mass; there was almost nothing else for him to do on a Sunday morning except for that; there were very few distractions.
Recall that prior to the Edict of Milan, Catechumens underwent a four-year process of discernment, Catechesis, conversion, and Mystagogia.
Those four Periods have been revived in the RCIA process. The Period of Inquiry (also known as the Period of Evangelization) is a time of introduction to the distinctive teachings of the Church. It is a time for Inquirers to be exposed to the essential teachings of the Church (including the Catholic definition of faith, the Nicene Creed and the Four Dogmas of Mary, among other things) discover the person of Christ, enter into a life of prayer, and begin to attend Mass regularly on Sundays. This period concludes with the Rite of Acceptance, and for those who were baptized in other Christian communities, the Church has given a Rite of Welcome that supplies for them what was lacking in their original Baptism (such as the mark of the Cross on their forehead by the priest and sponsor). The Rite of Acceptance is required for those preparing for Baptism, because it is the first movement of the Rite of Baptism as we see it in infant Baptism in the Catholic Church.
They then enter into the Period of Catechesis, where they learn the meaning of the Sacraments and come to a more academic understanding of the things they were exposed to during the Period of Inquiry. They also come to Mass every Sunday and take time at some point during the Lord’s Day to “break open the Word,” typically after Dismissal, which takes place after the Homily at Mass. Again, this goes back to an earlier form of the Mass in which the Liturgy of the Eucharist was open only to those in full communion with the Church. (Today, anyone can come to Mass and observe, but prior to the Edict of Milan, the Catechumens were dismissed after the homily even if they weren’t going to a session of Breaking Open the Word, because they were forbidden to be present at the Liturgy of the Eucharist.
This can be a stumbling-block and very confusing in an era of “we must be welcoming at all costs, no matter what” - but back in the day, the Church had no qualms about kicking people out who didn’t belong - yet.
The Dismissal Rite is a sober reminder to all of us that being Catholic is a privilege; not a right.
The Rite of Election concludes the Period of Catechesis and prepares the Catechumens to receive direct preparation for the Sacraments, and “initiates” them into (for lack of a better term) the Period of Purification, which is direct preparation for the Sacraments.
The Rite of Calling to Full Communion is given to those baptized previously in other churches, and to uncatechized Catholics who have been baptized but not confirmed. The reception of this Rite is what permits the parish priest to administer the Sacrament of Confirmation to those people; otherwise he is forbidden to do so.
You can’t initiate yourself into this; the Bishop calls you by name, individually, at the Rite of Election or at the Rite of Calling to Full Communion, in order to enable you to receive the Sacraments of Initiation at Easter.
You can get baptized in a puddle in a parking lot if you have to. It’s not like the rite is actually part of or required for baptizing someone.
Not in the Catholic Church, you can’t. And if you were baptized in a puddle in the parking lot, then you have to go through the Rite of Welcome and the Rite of Calling to Full Communion in order to make up for what was lacking in your parking lot puddle baptism.