I think Drow lore changed over time. The first official full description as far as I know (not far) was in 1978's Module D1-2, "Descent Into the Depths of the Earth" by Gygax. There it is written with incorrect punctuation:
"Most Drow clerics are female, and no upper limit to their level of ability is known, No male Drow cleric is able to go beyond 4th level."
It's all about the spiders ... the Drow are spiderists.