There is no next race, it’s an ongoing relay.

Different people living different lives is closer in analogy to different runners running different races, imo.

The marathon is infinitely long and we rank people on their positions every 5 miles.

That's not what they are suggesting. That's what you came up with as a solution for the problem which they presented. You're arguing against your own conclusion.

The implication is obvious from the context of the discussion. Don’t be disingenuous.

The implication might be obvious because that might be the most immediate solution to an evident problem. Just because the analogy works and you don't like the (obvious) solution it doesn't mean we should throw out the baby with the bathwater in the process.

This is how placement works in NASCAR races. Racers get an advantage in the next race based on the performance of this race.