Noooo, catechumens were dismissed before the Creed for reasons of operational security.
Seriously. Read the transcripts of St. Cyril of Jerusalem’s RCIA classes right before Easter and right after.
First, there’s a warning not to let people who aren’t members of the Church read this work, and to keep your big fat mouth shut about it.
Then St. Cyril warns the catechumens not to be trying to get Catholic so you can get magical witchcraft powers or whatever other rumors were going around. (This was not long after Catholicism became legal.) Then he starts to reveal the amazing secret teachings of the Church, most of which the catechumens don’t know. Like the Creed, which they are solemnly warned not to go repeating to non-Christians.
All they know is the readings, basically.
Then they go to Easter Vigil, still not knowing what a Mass really consists of, receive the Sacraments of Initiation as a total surprise, and have to go to classes to find out what the heck just happened to them – still being warned not to talk about secret stuff like Baptism and Communion and the Lord’s Prayer.
Now, non-Catholics do have valid Baptisms, but they aren’t Confirmed and they haven’t received Communion. So unless they were raised in Catholic families, they probably would have fallen under the whole operational security dealie in the early Church. (And yeah, the whole “their parents were involved in a heretical or schismatic Christian group” would not have been a plus, back then.)
I don’t think you need to be quite that authentic… but it’s certainly true that the Catholic Mass is not the same as liturgies in most liturgical Christian denominations, much less most non-liturgical ones. So even most Christians need to learn the Catholic way of doing things. But of course, priests and RCIA people should be looking out for individual needs, not just being cookie cutter.
If RCIA people are seriously worried about not receiving the graces of the final blessing, they can always come early and catch the end of the previous Mass, or go to Mass on Saturday or another Mass on Sunday for the uninterrupted experience.