#1 R&B not charting pop is indeed astonishing, and a type of trivia I really dig. I think the last R&B #1 to miss the Pop Top 40 was Roberta Flack's "Oasis," in that same time period. But we are close to one now: Jazmine Sullivan's "Need U Bad," #1 R&B the past two weeks, has been stuck in the 40s for a couple weeks, not moving up. iTunes gave her a promo bump (which is why I know the song; it's a strange reggae-tilted oversung wobbler), so we'll see.
Meantime, I'm currently watching on WLIW a Bill Joel concert on "The Old Grey Whistle Test" from 1978, doing a lot of Stranger songs. I have to admit that, Billy Joel fan though I've been all my life, it's hard for me to enjoy him in the live setting knowing what a pathetically creepy caricature he'd become in his later years.