I have all the things you've mentioned and no big three yet my electrical system is doing just fine, in fact, I monitor it via a voltmeter gauge I have installed in my car.
Just because you havn't had a short doesnt mean you don't have a flaw in your electrical system.
Go look at your fuse box in your house, theres a main breaker for the entire panel. The same thing applies in your car. You have one massive fuse called a fusible link. Google it, you'll find many articles on it. Its not necessary, but neither is any fuse for that matter but its recommended for safety reasons.
Just because it works without it doesnt mean you shouldn't have it.