13 recorded the OBCR before the show started previews and they still cut two numbers and altered lyrics and sections of others.
I get what you're saying, newintown. Most of the changes made nowadays a completely cosmetic, if changes are made at all. I saw The Last Ship again last night and I only noticed a handful of minor changes from the first preview.
Still, songs are still still cut and replaced. Scenes are rewritten and supporting characters are altered and/or dropped. Maybe the changes don't have the same magic results that "Before The Parade Passes By" had on Dolly, but there were plenty of shows back then too that made (large) changes and the final effect remained the same.
Cry-Baby, A Tale of Two Cities, 13, Bridges, Rocky and First Date all cut and/or replaced songs during previews. Maybe most of these shows were doomed from the start and it was just rearranging the chairs on the Titanic, but some creators do attempt to make meaningful changes- and I count the cutting of a song as a meaningful change.
Marie: Don't be in such a hurry about that pretty little chippy in Frisco.
Tony: Eh, she's a no chip!