In response to the OP, it is indeed a curiosity why tangential tracking arms are not in more widespread use. It seems that popularity among dealers, availability, leagacy and quality are certainly factors. The one thing that cannot be disputed is that pivotal tone arms are by their very design, distortion inducing devices due to their inherent tracking error regardless of the most popular alignment methods currently used (Uni-Din vs Lofgren/Baerwald). EVen at their best, 2nd order harmonic distortion is routinely up to 1%.
Lateral tracking error vs eccentricity
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And when alignment isn't perfect, distortion goes up further still.
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So, what's the big deal about 1-2% distortion? After all, many of our tube amps run at 2% distortion pretty regularly! Does distortion alone mandate favorability of one design over the other? Well, the answer is...it all depends! Execution is obviously a key factor. It's like the old argument; which is better, direct drive or belt drive? There is no right answer unless you are comparing one specific model to another. Maybe then, there is a satisfactory answer. But for goodness sake. I wish the advocates of pivoted arms would at least acknowledge that they are distortion inducing devices by their very nature. It's not the curse of death by any means and of course some of the best systems on the planet use them!
So often, orchestral pieces have large crescendos at the end and for that reason, if I had a pivoted arm, I would prefer the Uni-Din alignment. But better yet, my money is still on a good tangential design because I want that lower (to zero) tracking error across the entire record surface. I welcome the renewed interest by some manufacturers in the newer "classic" tangential designs, as well as the "hybrid" pivotal/linear trackers. There's a lot to look forward to in this area.
BTW, a classic reference on this subject is by Keith Howard published in Stereophile in 2010
https://www.stereophile.com/reference/arc_angles_optimizing_tonearm_geometry/index.html