For it to be scientifically accurate of a comparison, the ratio of weight:human needs to be equal to that of rider:horse, not a direct flip.
In case my phrasing is confusing, to illustrate what I mean here is an example: a 200lb horse carrying a 100lb human is equivalent to a 100lb human carrying a 50lb weight.
The horses also all had humans on their backs. To my knowledge, none of the humans had horses on their backs.
For it to be scientifically accurate of a comparison, the ratio of weight:human needs to be equal to that of rider:horse, not a direct flip.
In case my phrasing is confusing, to illustrate what I mean here is an example: a 200lb horse carrying a 100lb human is equivalent to a 100lb human carrying a 50lb weight.