Sorry, what does %GDP have to do with per capita GDP in the context of the comment, beside the size of population?

EDIT: I'm trying to highlight the fact that preindustrial productivity is a function of population size and therefore per capita GDP is not really a good measure in that context.

No, but explains a part of the decrease of those 25% once productivity stopped being a function of population size in at least a part of the world. Of course one has to recognize the values destroyed by western influence, otherwise the story will be far from complete, but I found the mention of those 25% rather loaded. One can study the past development of societies without being "a revisionist". It is as much possible to push for cheap apologetic revisionism as it is to get allergic reactions and to dismiss perfectly valid opinions as apologetic revisionism needlessly. Most of the time, post scripta to the effect of "BTW, don't respond with things that I won't like" seem like warning lamps to me, regardless of the topic.

From a moral perspective the point still stands, cheap exploitation and subjugation resulted in the current divergence. If the two societies diverged as a result of merely the technological and scientific advances but nothing more the yes your criticism is warranted. Long story short, someone had a better beat stick, nobody's is denying that, but the atrocities and exploitation still remain.