Parmandur
Book-Friend, he/him
I started playing with 3.x, and I personally gave the Prestoge Class concept bad marks in the uA survey at the time. Never again, please.UA in the 5e era almost never includes context/story/lore/fluff.
They tried the Rune Carver as a Prestige Class in a UA ages ago. I rather liked it, but also I was someone coming back to the game after 20 years away so I didn't understand the baggage.
I did like the proposed Multiple Class Subclasses, and I would personally have been fine if they had standardized progression to make that more feasible...but neither is it really necessary.