The "Boss" from Pusher is arguably the most famous climbing hold ever made. For a decade or more, every gym had one, but they were all unique. Lots of them had micro chips that became critical to usage of the hold. Some had decent texture and some were glassy smooth from years and years and years of use. A lot of the accidental variation in new holds has gone away as the industry has standardized around a handful of industrial fabricators like Aragon, but even over the course of a single indoor boulder problem's life, the accumulation of chalk, sweat, and shoe rubber can have a significant impact on how a hold climbs.
I guess the real question is, do these changes just make routes harder or do they make them fundamentally different? Do they actually change the set of moves that constitutes the easiest way to the top? To be honest, I'm not entirely sure. But it's something interesting to think about.