I think that has to do more with who you ask. There is no "concrete" definition of "Fine Art." This is not science, there are no absolutes except in the minds of those who hold strong opinions. Recognition [often] has nothing to do with quality. Works on paper are seen as somewhat less "permanent" though. There is a greater likelihood that a work on paper will "degrade" or be damaged as time passes. That has more to do with preservation though.-TJ
Tradition has always include work on paper as a Fine Art.
Watercolor is ancient and began in China. Color pigments were introduced much much earlier historically. Watercolor are in the fresco techniques of Santorini, on cave paintings. Easel oil painting began with Georgio in Venice around the 14th-15 th cent. (see Mary McCarty- Venice Observed)