Lol, but actual-serious, straw is an ecologically sustainable form of insulation if treated properly, and doesn't carry many of the health risks for workers or residents associated with fiberglass insulation. There's trade-offs, but it's a viable alternative in many parts of the world.
Yeah, just not really fire resistant like glass or mineral fibre. Most fire codes are not permissive of flammable insulation. Same reason you don’t see plain cotton or wool in current construction.