Your sterotypical grandfather who worked 9-5 and earned enough every five years to buy a new house in a relatively middle-of-the-road job did so because of a prosperity boom following WW2 which was built on the back of repairing economic hardship and was a rather unique time in history even for being a boom portion of the cycle. Compare that to your father working in the 70s where twice annual cost-of-living adjustments to account for rapid inflation were the norm - or the 1920s and earlier in America where the majority of people suffered under absolutely atrocious working conditions and lived entire lives trapped in debt cycles to a single company.

It ebbs and it flows - there are times in history you can fondly remember for their plenty and times you can remember for their scarcity.

The only really new trend, IMO, is that in the modern world (I think for the first time ever) working continuously for the same company is a financial trap. The strangest innovation of the current day is that churn is accepted and retaining skilled employees is de-emphasized compared to... hiring new replacement employees with less skill. This incredibly bonkers habit has gained wide enough acceptance that it's sort of the default business state.