Well, it works well on wood. I can't use it to fix plastic or ceramic or metal. It's not ultimate or versatile. I guess you often handle materials that it works well on.
You did say you use wood glue whenever you're using wood. So?
There are different substances that can be called wood glue. There are bottled creamy one-part concoctions based on PVA but even then more than one kind: Titebond makes 3 (classic, water resistant and generally improved, waterproof) plus viscus varities for trim (high initial tack).
Then there is powder that you mix with water, (Weldwood brand comes to mind) and different kinds of hide glue. I used fish-skin glue to fix a Chinese strinnged instrument, to be authentic.
As for gluing wood with stuff not specifially sold as wood glue, there is epoxy and polyurethane glue and cyanoacrolate glues good for mixed material joints but useful for just wood sometimes: instant bond, no clamping pressure, void filling, etc.
It can also be handy to use a hot-melt glue gun.
So why use only one? Even among the PVA group, if it works OK why do you need more than one? If you had to go beyond the feature set of your stand-by bottle, you would. If you wanted to optimize the joint, you could if you were an enthusiast and didn't mind de-optimizing for ease and convenience.
If I were attaching one piece of trim, I'd note the issues with "regular" glue, but then I'm done. Faced with a large project and remembering that experience, I'd pick up a bottle of "Titebond for trim" when I noticed it on the run to buy supplies. And so your collection grows.
For outdoor chairs, I saw yankee workshop use marine glue from a caulking cylinder dispenser. And that's wood-on-wood.
For occasional and varied uses, you buy what's sold as general-purpose. So instead of asking “why do I always use this?”, you should note: “Isn't it great that there is a general-purpose versitile product that has a long shelf life and works reasonably well on so many tasks?” no surprise that this is what you keep in your garrage.