why did the west commit to multiculturalism?

[Watchman]

Eh, no... you were talking about the 19th century nationalist unifications in Europe. It's just not a relevant argument in a thread about modern day multiculturalism and its issues.

Really? 'Cause I daresay the nationalist projects of the Long Nineteenth Century, and especially their many failings and ugly sideshows as well as the fact they were engaged in to begin with, rather illustrate why "multiculturalism" ended up as de rigueur.
Ie. because the alternatives were found out to be rather vile and unworkable.