Da’at or not?

Anytime I make any adjustment to the sefirot of the Tree of Life historical organization, I get attacked. But these same attackers fell perfectly free to pontificate upon the sefira of Da’at.

Da’at is known as the eleventh sefira. Here is a link regarding what Da’at is suppose to represent: WIKIPEDIA.

This has never made sense to me. The oldest (and presumably the purest) source of Kabbalah and the concept of the ten sefirot is the Book of Creation (Sefer Yetzirah). But, the Sefer Yetzirah has a very specific prohibition against an eleventh sefira:

“Ten are the numbers of the ineffable Sephiroth, ten and not nine, ten and not eleven. Learn this wisdom, and be wise in the understanding of it, investigate these numbers, and draw knowledge from them, fix the design in its purity, and pass from it to its Creator seated on his throne.” (Sefer Yetzirah, Wescott, Chapter 1:4).

If the very source of Kabbalah tells us there are not eleven sefira, but ten, why do so many inject Da’at into the mix?

And if we use eleven sefirot, perhaps we miss other important understandings of the number ten. Here is a link to a discussion I participated in over at BackYardProfessor.com that illustrates the importance of maintaining the pure symbolism.