> Wasn't this supposed to happen when PCs came out?
Did it not?
PCs may not have caused a catastrophic level of unemployment, but as they say "past performance is not a guarantee of future results." As automation gets more and more capable, it's foolish to point to past iterations as "proof" that this (or some future) iteration of automation will also be fine.
Some people managed to retrain and adapt, partially thanks to software becoming much more intuitive to use over the years. We don't know how big the knowledge gap will be when the next big wave of automation comes. If retraining is not feasible for those at risk of losing their careers, there better be welfare abundance or society will be in great turmoil. High unemployment & destitution is the single most fundamental factor of social upheavel throughout human history.
Then new ideologies and social movements emerged with the explicit purpose of making things better, which caused changes to happen for the better.