It doesn't take a lot to recreate the capitalism to feudalism pipeline. If you have currency, small imbalances in resources and needs compound over time, creating imbalances in wealth. Imbalances in wealth provide the opportunity to leverage that imbalance for further wealth by way of rentseeking. Wealth provides power which provides more wealth and more power. Eventually your landlords drop the "land" prefix and simply become nobility.

Prior to the invention of currency, we had reputation economies. One might be tempted to model such economies as just money economies with implicit ledgers, but that isn't how reputation works in the real world. Being implicit, reputation captures a lot of activity that doesn't warrant an overt exchange of currency. Think of all the things that you appreciate, and make you value a relationship with someone more, that would be terribly inappropriate to pay them for: the friendly guy at the pub who tells you stories of questionable accuracy, a fellow parent watching your kid during a playdate, anything in the romantic sphere at all. Reputation also doesn't add up in anything close to a linear way: The guy who did something really big once and the guy who did something small with extreme regularly over a long period of time both likely have stronger ties with others in their community than the one who sporadically provided middling value. Reputation also isn't particularly inheritable: I might feel some obligation to someone's kid because of my relationship with their father, but that obligation fades rapidly as they entire adulthood, and nobody owes you shit for who your grandfather was. Likewise, gifts from someone who has an embarrassment of excess are valued much less than the same thing offered by someone who has barely enough.

All told, reputation economies act as a damping function on wealth and power accumulation, whereas currency economies provide positive feedback on the same.