It's your metabolism that produces that junk with increasing ratio of stuff that you need. If you just remove blood, the ratio of good stuff to bad stuff does not change. Same with kidney filtering if they can't recognize the difference.
Blood transfusion from younger person gives you blood with better ratio.
> [20] Mehdipour, M. et al. “Rejuvenation of three germ layers tissues by exchanging old blood plasma with saline-albumin.” Aging 12(10), 8790–8819, 2020. The UC Berkeley team found that diluting old blood plasma with saline and albumin produced rejuvenating effects comparable to young blood — suggesting the mechanism is removing pro-aging factors rather than adding youth factors. This was, at the time of publication, the strongest evidence that old blood is the problem, not that young blood is the solution.
Maybe regularly donating blood would have more negative effects from losing good stuff than positive effects from losing bad stuff, or maybe not. There is evidence that it could be a net positive though.
And even aside from the buildup of crud due to normal aging, environmental crud (nano/microplastics, PFAS, etc) is not produced by the body. It's still not totally settled science whether all of those things have negative effects, but regular blood donation would help clear it out, at least a little.
But a further horror is: you’re dumping your crud on the person getting your transfusion? I guess it’s better than dying in ER.
dilution = change of ratio. Just giving blood is not dilution.