I’ve had some different vintages of Cakebread’s “Rubaiyat” over the years, which is a syrah-pinot blend, some years including zinfandel, merlot and/or other varieties in the blend, and it’s quite a good and interesting wine.
Domaine Alfred (now Chamisal winery) used to make an inexpensive pinot-syrah blend called the DA Red, that was a solid quaffer for $10-15.
My guesses as to why you don’t see it more often would be (a) the cost, as several people noted above, and (b) that it’s just not traditional to blend pinot noir, other than in sparkling wine. Notice how you rarely see chardonnay blended either, that being the other main grape from Burgundy.