Who said anyone’s life lacked value? There’s nothing wrong with being a market clerk, or a restaurant server, or a farm laborer, or a fashion model, or an administrative assistant, or a factory worker, or a janitor, or a soldier, or a mail carrier, or a taxi driver, or a stay-at-home parent, ....

The problem is that many people in many places are stuck with a choice of either working themselves to death at a job they hate for shit pay and no benefits (or maybe just starving on the street) or else selling themselves to a very wealthy asshole. When that happens, it indicates a profound structural failing of the society. Prostitution or feudal servitude shouldn’t be anyone’s only shot at a comfortable life.

In theory there’s nothing wrong with a career in private security. But it’s messed up to be an enforcer for the dictator family who who rule Equatorial Guinea and live lavishly while keeping the rest of the country in miserable squalor.

In theory there’s nothing wrong with being an actress. But it’s messed up if getting a leading part depends on giving blowjobs to the studio executives.

Etc.

> It does not imply a "power imbalance".

If the young women in such relationships had all the money and power and the old men had none, how many of those couples would still be sleeping together?