There are two types of things - multipurpose and single purpose.

Using the TAO of Alton Brown - never buy a single purpose item, except for a fire extinguisher.

When I pack to go out in the weeds, almost every item has a second and sometimes third use. If not, I really have to think about if I need it, and what can take its' place.

Just to clarify, I would never pack a hook knife on a real backpacking hike. I just bring a heavy pack loaded with toys when I dayhike.

On the other hand, humans are very creative. I seriously doubt that any truly single-purpose tools exist.

Hmmm... just eyeballing my deck of cards.... Whittling a spoon could be more fun than solitaire. Of course, it's fun for only one, and I could use my cards as tinder or a defensive weapon.

Although a deck of cards would stretch my definition of 'tool', they could be useful in an emergency too. Like making emergency snow-blindness goggles, shoe or moccasin lining, Plastic cards could be used with pine pitch to fix a small hole in a canoe, trail markers, finger splint.....