Whenever I read a how-to article, the common refrain is “can’t ever have too many clamps”.
This, again, is where we can look to the past for a solution.
For 95% of woodworking history, metal was ridiculously expensive and clamps were wooden wedges or even specifically shaped branches used to hold work while you worked. Craftsmen had to think of other ways to lock joints together. During much of this period, glue was either non-existent or not relied on for much more than a temp solution.
With many modern techniques, the idea is to use modern glue to hold the two pieces of wood together. The woodworker of today soothes themselves on the knowledge that the glue line is stronger than the wood around it. Clearly, nothing will happen that could cause that glue line to fail.
So then they are encouraged to continually hoard clamps of ever increasing complexity and cost as if they are canteens of water in the Sahara.
In this example, I am joining the wood using mortise and tenon joints. Basically, think “Tab A into Slot B”. This is a great joint in that there are a whole lot of directions that the joint will never move in. For modern woodworkers they will use glue alone to ensure the joint doesn’t move in the one direction it can move in.
The problem is that you can’t guarantee that the joint won’t move in that direction, even just a little. With glue only, once that joint moves a little, you might as well not even have anything holding those joints together. This is where a simple pin of wood can save the day.
On these joints, the glue can fail all it wants, but the boards will stay fastened together until the wood itself rots apart. In today’s throwaway society, being able to use something for generations, just because the builder thought like an old-timer, has tremendous value.
Sometimes, you can even use these dowels to make an artistic statement. Note: this isn’t my image, I grabbed it off a Google Image Search so I can’t attest that they are functional dowels. Some folks use trickery to hide screws, but this proves the point well enough.