Yes, I know that, but what Scripture has to say about the matter is what all of us who say we believe in the Bible as God's word should settle it, no?
Exactly. We are speaking of two different things there. That being so, there is no basis for saying that the first one is not needed, simply because of how we understand the second one.
Here is an interesting quote from an old Quaker writer Robert Barclays (and no I am not a Quaker).
“First, that there is but one baptism, as well as but one Lord, one faith,...”
As for the first, viz., "that there is but one baptism," there needs no other proof than the words of the text (Eph. 4:5): "One Lord, one faith, one baptism"; where the apostle positively and plainly affirms, that as there is but one body, one Spirit, one faith, one God, &c., so there is but one baptism.
Obj. As to what is commonly alleged by way of explanation upon the text, that the baptism of water and of the Spirit make up this one baptism, by virtue of the sacramental union.
Answ. I answer, This exposition hath taken place not because grounded upon the testimony of the Scripture but because it wrests the Scripture to make it suit to their principle of water baptism, and so there needs no other reply but to deny it, as being repugnant to the plain words of the text, which saith not that there are two baptisms, to wit, one of water, the other of the Spirit, which do make up one baptism, but plainly, that there is "one baptism," as there is "one faith" and "one God." Now there goeth not two faiths, nor two Gods, nor two Spirits, nor two bodies, whereof the one is outward and elementary and the other spiritual and pure, to the making up of the one faith, the one God, the one body, and the one Spirit; so neither ought there to go two baptisms to make up the one baptism.
Obj. But secondly, if it be said the baptism is but one, whereof water is the one part, to wit, the sign; and the Spirit, the thing signified, the other.
Answ. I answer, this yet more confirmeth our doctrine, for, if water be only the sign, it is not the matter of the one baptism (as shall further hereafter by its definition in Scripture appear), and we are to take the one baptism for the matter of it, not for the sign, or figure and type, that went before, even as where Christ is called the "one offering" in Scripture though he was typified by many sacrifices and offerings under the Law, we understand only by the one offering, his offering himself upon the cross, whereof though those many offerings were figures and types, yet we say not that they go together with that offering of Christ to make up the one offering; so neither, though water baptism was a sign of Christ's baptism, will it follow that it goeth now to make up the baptism of Christ. If any should be so absurd as to affirm that this one baptism here were the baptism of water and not of the Spirit, that were foolishly to contradict the positive testimony of the Scripture, which saith the contrary, as by what followeth will more amply appear.”