It's like most stuff in the shops, it's made to sell not to use, and people who might buy it (**) probably don't realize until they get it home that there's no "magnetic" place to stick it on a computer.
If it's small enough, and "cute enough," it goes on the refrigerator, since that's the only appliance in most houses that a magnet will stick to. The only other place you could put it would be on the washer/dryer, but then nobody would see it and know how clever you were when you bought the same p.o.s. everybody else has on their refrigerator.
It's a rule of modern marketing that anything that can be screen printed will eventually be made into a refrigerator magnet.
** There hasn't been enough steel inside (##) any automobile sold in the US in the past 30 years or so to bother your dashmount compass, but they still sell "magnetic mount" accessories to stick on your dashboard (which is entirely made of plastic). Those "**" people apparently still buy enough of them to make it worthwhile for retailers to keep them on the shelves.
## With some "modern" cars, there isn't enough steel on the outside to hold your mag-base CB antenna in place.