> most European countries that operate in a redistribution system

The Netherlands does not. [1] It is also considered one of the best-run pension systems in the world.

> the current workers pay the pensions of the current pensioners in exchange for "IOU tokens", the US has everyone responsible for themselves

US Social Security works in the manner you described - current workers pay for current pensioners. This doesn't work great as we already know.

Making assets instead of workers pay for pensions isn't a bad idea per se. It makes no sense to load workers down with taxes to pay for seniors. The math only works as long as the population of workers grows or if you tax workers more and more.

Workers' labor produces ever-increasing surpluses every year. Use those surpluses aka higher productivity to support seniors.

1. https://ec.europa.eu/finance/docs/policy/191216-insurers-pen...