No it’s not. If the increased productivity is realized by multiple industries, then they all compete on price and the price of their goods comes down. That means the consumers of the product capture the gains in productivity.
Farmers using machinery instead of labor has meant cheaper food for everyone, not rich farmers.
I think that if we look at inflation-adjusted productivity, and inflation-adjusted average income, then that would indeed prove increasing inequality, right?
I believe the chart in this link is adjusted by inflation. Showing overall the same trend:
