Well, according to the 2e Priest's spell compendium, over 400 priest spells were added just between 1995 and 1997, which is more than the amount of Wizard spells in the PHB. Sadly, neither it nor the Wizard's spell compendium has a comprehensive number that's easy to find, but the INDEX of the Priest compendium (all three books of it) is 19 pages long, and the Wizard spell compendium is comprised of four books, so Fanaelialae's claims are quite credible.
However, while 5e doesn't have nearly this kind of amount of spells, the truth is, when you consider that 2e and 3e had a very different kind of production format, with tons of books coming out every year, not to mention Dragon magazine coming out monthly, WotC still cranks out way more spells than anything else- races, subclasses, feats, magic items, backgrounds, or equipment. Hence my comment that, despite their conservative production of new player facing material, there's still a whole heap of spells, and more being printed all the time.