The reason is economic growth for the company / the country.
This in turn is a more subtle point than it seems at first glance. Not having economic growth isn't really a desirable option for a company, a country, or in (the long run) the people involved.
https://en.wikipedia.org/wiki/Great_Compression
Outside of that small 20ish year window, workers have never benefitted from increased productivity compared to the capitalists that have stolen $50 trillion from the masses:
https://time.com/5888024/50-trillion-income-inequality-ameri...
That said, ppp adjusted median houshold income has grown fairly steadily even in the US, even with growing inequality... so workers too have benefitted, just not as much as they could of the gains had been spread more evenly