For me it was 3.5 Unearthed Arcana with its inclusion in the SRD and Pathfinder where they became common options.
The older brother of one of my gaming friends had the issue of Dragon or the Best of Dragon with it so I let him play one the few times he was around in the 80s. Otherwise it was a class that was referenced a bunch in Dragon and in discussions but was otherwise sort of mythical for my gaming circles because none of my friends had any solid details on its specifics, just second hand references.
I eventually got the Dragon Archive CD and was able to read about them and the paladin of every alignment articles.
Specialty priests were the most common non-PH class I saw in the 90s.
Googling around I just saw that the Dragon Archive CD existed. How was the scan quality?