Tampons absorb, which isn’t great if you need to help clot your leaky flesh. It’s better than nothing, but gauze or tissue would be better.
Tampons absorb to grow thicker and then staunch the bleeding by blocking it. It’s literally called a tamponade.
They were invented to plug bullet wounds in wartime after all, until nurses noticed they had other practical uses as well.
Don’t quote me on that though, I don’t remember where I read that.
Tampons have been used to manage menstruation for thousands of years. In the 1800s they first started trying to used them for bullet wounds. So they weren’t invented for bullet wounds.
Also, just to be clear, don’t stick a tampon in a bullet wound. They are not at all an effective dressing. In all cases you are far better off just holding a wad of gauze or similar over the wound and applying pressure. A tampon isn’t large enough and doesn’t go deep enough to do any good as packing.