Because baptism of blood and desire require an act of the will
Saint Paul talks about those who through no fault of their own do not know Christ and he says that can be saved.
Are you familiar with Church teaching on invincible ignorance?.. now could there be stronger invincible ignorance than in infant?
the official teaching of the Church is that those who die in mortal sin or in original sin alone both go to hell but suffer unequal punishments
For what it’s worth Church never states that “all” of those… but that those… technically it still allows for exception such as with infants. Extra Ecclesiam Nulla Salus is also a dogma and yet we understand that invincible ignorance exists. I think that interpretation and circumstances matter more than official declaration in this scenario. At the same time, Church says “those who die in original Sin” and God can work outside Sacraments to purify. God does not punish us for what is not up to us- hence if baby dies before birth, or if there is invincible ignorance, mercy should apply.
In Orthodox Church, Augustine of Hippo is not saint, because of this.
Ecumenical Council of Constantinople states this:
logy mentioned (just as there is none for most saints of the Church):
We further declare that
we hold fast to the decrees of the four Councils, and in every way follow the holy Fathers, Athanasius, Hilary, Basil, Gregory the Theologian, Gregory of Nyssa, Ambrose, Theophilus, John (Chrysostom) of Constantinople, Cyril,
Augustine, Proclus, Leo and their writings on the true faith.
So… yeah.
I will just say that I find myself agreeing with the Eastern Church on this particular subject.
Council of Carthage was accepted by 7th Ecumenical Council (which is accepted by the East of course). Council of Carthage teaches:
"
whosoever denies that infants newly from their mother’s wombs should be baptized, or
says that baptism is for remission of sins, but
that they derive from Adam no original sin, which
needs to be removed by the laver of regeneration , from whence the conclusion follows, that in them the form of baptism for the remission of sins, is to be understood as false and not true,
let him be anathema ".
Clearly Eastern Church also states that Original Sin “needs” to be removed by Baptism.