9 x 12 in/20 x 30 cm
Hardly. Artists and painters have always--and by always I mean since the Dark Ages became the Renaissance--used whatever was available to render their art.
Earthly powders and elements dissolved in different kinds of oil, or water, have been used for a long, long, okay one more long, time. Later those same elements among others were ground and bound into pastels for drawing/painting. Ditto for drawing with coal and graphite-like tools.
The point is painters didn't appear to limit their media to only one accepted thing, and they didn't look with suspicion on new-fangled inventions. Although there was initial resistance to the impressionist style, remember, it was the Impressionists who embraced the newly-developed paint in tubes that encouraged painting en plein air in addition to the use of photography.
So why isn't acrylic considered a fine art medium, and why aren't impressionistic plein air acrylic paintings not considered fine art?
You tell me.