The most compelling argument from that other thread wasn't that AI isn't improving productivity, it's that companies never hired Junior engineers to increase productivity in the first place! Unless you win the lottery in hiring having a Junior on board slows you down as you teach them and ramp them up until they stop being a Junior.

Companies hired Juniors as a way to invest in someone who could be a valuable asset later, without having to compete quite so hard for people with strong potential. What's changed is that companies don't have as much financial flexibility as they did before (interest rate and tax code changes) and the first thing to go is risky long-term investments in hiring and retaining talent. That takes the form of cutting back on cushy benefits and it also takes the form of cutting jobs for Juniors.