I (being a somewhat politically-minded sort) noticed some parallels between the Yeats’ observations on the problems with the various Irish Nationalist movements and similar groups in the present and recent past. Simply put, the “Curse of Heterogeneity” Yeats decries (and wrote The Only Jealousy of Emer in a sort of protest to) is what brings down a lot of movements that seek changes in the social order; it’s why the Tea Party movement gained so much ground and became a major force in American politics while the Occupy Wall Street protests (and those they spurred elsewhere in the world) largely went nowhere: Progressive politics can mean many things, while the message of Conservativism is very simple and easy to swallow. “We want to change things” can’t be a rallying cry because it demands further specificity, while “keep things the way they are” (while not terribly catchy) tells you all you need to know.
Yeats, having orbited Maude Gonne, written plays with Augusta Gregory, and watched Synge and other Irish poets try and fail to spark a sustainable revolution, had seen this factionalism doom Irish culture to what seemed to him a slow, painful, middle-class death. His trepidation was understandable.