It is sane and inevitably correct to treat with extreme skepticism any explanation for an economic effect that reduces the cause to a singular source. AI is to blame, to an extent, so is remote working (it is excellent for older folks who have lives to support but is a rug pull on the social aspects of office working), but the economy is the big looming threat here. We still hadn't recovered fully from the pandemic and then we got Trump 2: Electric Tariffoo which has wrought absolute havoc on business stability. All these combine (with other factors like the ever growing PE investment) to discourage innovation and long term investment.

Junior employees are a long term investment - if the R&D budget is frozen, you're sure as heck not going to dump 60% of your budget into onboarding.