Because the wall it hangs on is outdoors. Outdoor-grade vinyl sheds rain without the ink running or the print buckling, and the metal grommets let it be tied to the frame instead of taped to a wall panel. Paper prints do not survive their first storm.
Cable ties or S-hooks through the grommets, attached to the sukkah frame, with all four corners fastened so the print stays flat in the wind. Fixing only the top two corners is what causes the grommet tears you find the following year.
They suit different walls. Tova Shaaryashuv's gedolim portraits are the pieces guests study during the meal and generally take the main wall. Gita Stern's 11-by-17 prints hang well in groups and fill smaller spaces. Chaya Hindy's larger pieces work as a single statement on a side wall.
Rolled, never folded — a crease in vinyl is permanent. Take them down completely dry, roll them loosely with the printed side out, and store the roll where nothing will be stacked on it. Stored that way they last many seasons.