If European collectors began liking Impressionist art in the early twentieth century, what connection does that have to Japanese collectors 80 years later? As far as we know, none—this is irrelevant.

This doesn’t tell us anything about why Japanese collectors were so interested in nineteenth-century Impressionism, so it's not relevant to the argument.

Nineteenth-century Impressionist paintings borrowed from esteemed Japanese prints, so the paintings certainly had aesthetic elements that Japanese collectors would appreciate. This supports the idea that the preference was aesthetic.

In previous decades, Impressionist art had been very valuable. If anything, this suggests an economic motive for buying Impressionist art: what if it rose in price again? That certainly doesn't support the argument.

The fact that some Japanese artists were globally popular doesn't tell us anything useful about nineteenth-century Impressionism and Japanese collectors. This is irrelevant to the argument.