I think the shipper fights gave the writers indication of what was most popular in the show and I definitely think a lot of the CHOSEN script was proof that Joss was aware of the A/B/S triangle popularity. I've never seen Angel and Spike more petty than they did about each other in that episode
and it carried on into Season 4 of 'Angel'.
Sadly, I think the Buffy/Xander fandom had been majorly sidelined by that point. Otherwise, Joss might have actually taken Sarah and Nick seriously when they requested BX.