Because that section was rescinded with the passing of the amendments (I think 13 or 14.)
That means, when reading the Constitution, you can and should literally skip that portion.
The Preamble is not part of the Constitution, just as a forward to a book is not part of the book.
I defy you to find a copy of the Constitution that does not include the language before the amendment and the amendment; else, how you would know what was amended.
When were amendments 9 & 10 rescinded?