About 20-40% of the population seem to be constitutionally unable to save, so any time a population gets wealthier the rich tend get richer because if property rights exist someone is going to end up owning any new wealth.
There isn't any inconsistency with the article's commentary and the observation that it was better to be a peasant post-plague than pre-plague. The rich got richer, the merchants became fabulously wealthy and the poor became better off.
The important trend here is that power moved from aristocratic landowners, who aren't really that bright as a class, to merchants who tend to be pretty clued up.
There isn't any inconsistency with the article's commentary and the observation that it was better to be a peasant post-plague than pre-plague. The rich got richer, the merchants became fabulously wealthy and the poor became better off.
The important trend here is that power moved from aristocratic landowners, who aren't really that bright as a class, to merchants who tend to be pretty clued up.