Like watercolor paper, these papers should have the strength to resist the effects of water soaking. Therefore the long length cotton content is important.
Etching papers often are passed through the press repeatedly, i.e. once per color while block printing requires a thinner rag paper so as to conform to the cuts and marks in the block. Silk screen is best as a hard smooth paper that shows the hard edge of the ink mark on silk screen.
You can see each print making technique requires a different paper.