Using ATX power supply in industrial electronic projects
Consumer products such as power supplies are not designed to last all that long, and especially are not designed to withstand wide temperature variations (in particular to start or work at low temperatures and not to self-destruct at high temperatures). They are often not supplied in housings suitable for industrial use. In some cases (though this does not necessarily apply to power supplies) they have a short design life compared to the expected decade or two for an industrial product.
You could certainly use an ATX supply in an industrial design if you are willing to work around those problems. I know of military products that use consumer innards and are ruggedized by adding housings and expensive connectors. Naturally the price goes up by an order of magnitude or more.
Brick power supplies are not made in the same quantity as consumer supplies, nor are they subject to the same competitive pressures, but they tend to benefit from the economies of scale in consumer products, otherwise they would be much more expensive than they are.