It is more than “an original purpose”, it has been shown that serving at the altar encourages priestly vocations. That comes directly from the Vatican
Indeed, the obligation to support groups of altar boys will always remain, not least of all due to the well known assistance that such programs have provided since time immemorial in encouraging future priestly vocations (cf. ibid.)
A great example is my own parish. We have only altar boys, and that has been true for at least the last decade since the pastor has been here.
Out of a parish of about 950 families, we have 1-2 men from our parish go into the seminary each year. We have had 12 men from our parish ordained to the priesthood in the last 10 years. We have 4 in the seminary right now, at various stages, which is actually a record low

2 are studying for the diocesan priesthood, and two for the priesthood in religious life.
The record of similarly sized parishes in our Archdiocese (or even those that are much larger) that have altar girls, is substantially less.
Bruce, what size is your parish, and how many men have been ordained from your parish in the last several years?