The material at Grenfell was not the same as the EIFS in this article. Not even close. Polystyrene is not the same as polyisocyanurate, though reporters and those not in the building industry could be forgiven for mistaking the two.

Grenfell used Reynobond Aluminum composite panels over Celotex polyisocyanurate insulation.

It wasn't some cheap alternative insulation material. Actually quite the opposite. Polyisocyanurate is used on virtually every ICI building project on the planet because it

a) has the best R value per inch, and

b) is rigid enough to support snow loads/can be used as a structural substrate to form ridges and valleys for drainage.