That's only for one form of explosion protection. Some methods of protection are for explosion prevention, other forms are mitigation.

Explosion proof / flame proof enclosures don't prevent explosions. Their sole purpose is to contain the explosion and to ensure that the gases escaping from the enclosure do not ignite the surrounding atmosphere. The beauty of a flameproof enclosure is that I can put standard, non-protected electronics into an enclosure and use them in a hazardous area. It's a much more affordable way of deploying electronics into hazardous areas, rather than designing from scratch and certifying.