if gypsum board (sheet rock) is so prone to mold, why do we use it?

"dry" wall?

uh costs

It's relatively an inexpensive wall covering that is easy to install, paint, and repair.

They now make paperless drywall products that are mold resistant.

Wait, you don't think wood is prone to mold?

People aren't going to use different materials for their walls, but I bet that the stained concrete guys are about to get filthy rich.

Walls were frequently covered in cheesecloth and paper over shiplap boards or were plastered. Plaster walls are more similar to Sheetrock without the weight or expense. They are also much more difficult to repair once damaged.

Sheetrock is the cheap route that also provides a fire rating.

It is abundant, cheap, fire resistant, has good sound insulation properties, is easily repaired, easily painted, and even offers some R value.

Cheap, easily repairable, easy to alter the appearance and it doesn't burn easily like say ....WOOD