Every other two-digit total in a life path calculation gets folded down to one digit. 11 is one of exactly three exceptions most Western schools recognize, alongside 22 and 33 — the so-called master numbers.
The reasoning offered is usually symbolic: repeated digits are read as carrying extra intensity, too significant to flatten into a single number. Whether that's a meaningful distinction or simply an inherited rule is a fair question, and one numerology's own literature doesn't fully resolve.
