"Nothing" is a very large statement to make. Would you take the rough equivalent in your tradition -- the dedication of an infant -- and say it means "nothing"?
Years ago I realized that my friends in adult baptism traditions were doing something very different in baptism than the infant baptism I had been raised with. Here's how I finally came to understand it:
In adult baptism, the baptism itself is much like a wedding ceremony. (I'm speaking in metaphors, here, not with any theological precision but in large strokes.) The person being baptized has met Jesus and fallen in love, and the baptism is a public declaration of love and commitment on both parts. It is the public expression of a lifetime covenant.
Infant baptism, on the other hand, is nothing like a wedding. It is more like an adoption. Does an adopted baby have a choice about its adoptive parents? No. The parents do the choosing, the legal transactions, the nurturing, etc. Infant baptism looks to Jesus Christ as the initiator and sustainer of the relationship and the parents, sponsors, and congregation as the earthly nurturers of faith. I say again, infant baptism is nothing like a wedding. Such baptism of helpless infants will never satisfy an adult baptism-oriented person as a true "baptism." The infant who is baptized obviously needs to grow into the faith they have been promised. They need to take ownership of it, to meet Jesus and fall in love with him for themselves, to play with the wedding metaphor.
Can you see that the baptism of an infant, while it does not meet your criteria for what a "baptism" is, can be very meaningful in another tradition? Like I said, "nothing" may be more (or less) than you wanted to say. I am not defending infant baptism as theologically perfect -- but I am not willing to say that it is meaningless, either. I have lived all my life in a relationship with Jesus Christ -- quite meaningful to me! -- that has its deepest beginnings in just such a "meaningless" baptism.
Even so, come Lord Jesus