I think the idea being expressed by the post you have quoted is that Japan "proved" itself to be a power when it won the war with Russia in the first decade of the twentieth century.
Yeah, but by then it already was a power, the Europeans just hadn´t realized it yet
Of course, a modernized China would sooner or later be tangled into a war, and a TL featuring it would probably be made more interesting by something like a chinese victory over a european power.