They are no different to any other tool. If you need to use one then you get the one that you need. If you have different uses (penknife for small cutting duties, skinning knife for dealing with game, woodcraft knife, etc.) then you will have different knives. If you don’t use them, but like them you can also collect them. You can insert any other tool in to this argument (drills, axes, planes, screwdrivers, etc.), but you will always get some nutjobs who get them because they think it makes them some way better.
A friend of ours has a son who has just made his first hunting knife. He has built a forge, made the handle, crafted a leather sheath and then uses it out when he is camping. That is a great range of skills for an 11 year old and he will use that when he needs it. Parents know he does not carry it as it is with the rest of his camping kit (stove, fire lighting kit…) so they are just impressed at what he has done. Is that wrong? Not in my view, but you may be different. It takes all sorts and I would trust somebody like that with as many knives as he likes.