I guess I'm a "contrarian", in that I don't routinely carry a multitool or a fixed blade. I like to keep things simple, so maybe that makes me a "simpleton"?

I always carry a modest folder. At work that't usually a Gerber LST. Very lightweight, thin and unobtrusive in the pocket of my slacks, and quite adequate for my needs. Outside of work I usually carry a SAK instead. About the only time I don't have a knife in my pocket is when it is forbidden, such as when I'm on a commercial flight. If I'm out in the boonies I generally have a short lanyard in my pocket. On it is a folder, a waterproof match case, a Windmill stormproof lighter, and a small compass. I find I can usually manage firebuilding quite well enough without a fixed blade.

With an nod to hikermor, we don't have cactus around here, and such spines as we have (notably devils club) are best dealt with using tweazers. I don't do much technical climbing anymore so I don't need to deal with stuck locking biners. I spend a lot of time outdoors but in general I don't find that I need a multitool for most of my outdoor activities. Therefore I don't see the point of carrying the weight. As the old saying goes: "When in doubt...leave it out!"

Pliers, screw drivers etc are most useful when one has to deal with nuts, bolts, screws, cotter pins etc. Therefore I do carry a multitool occaisionally in situations where it is more likely to be useful. I usually have one on if I'm fishing or messing around on boats. I often carry one while doing chores at home. When backpacking it is nice to have one multi in the group in case we need to do a field repair on a stove. When sea kayaking I carry a small repair kit which includes a multi, in case we need to fix a rudder or something of that nature. Getting entangled is always a hazard on the water, so I have a stout fixed blade serrated "river knife" on my PFD.

Those are my choices, based on my experience and my situation. Your experience, your situation, and your choices may of course differ.