It absolutely is possible to prevent dust from happening. Festool has proven this, and the well designed dust collection on their tools works just fine with their vacuum. However, I don't have the kind of money to afford Festool gear.
Here is something I knocked out recently.
That's a piece of 1-1/4" EMT elbow squeezed to round on one end and flattened a little on the other to fit the router's opening, welded to a cutoff of shelf bracket that fits the hose clamp. Since the router spins in one direction, it throws dust in a predictable path, and this catches 100% of what it generates, even though it seems to be visually quite "open". The actual Bosch base clogs up, and makes things run way too hot. This lets the dust go right into the vacuum, and keeps the airflow keeping things cool.
With the tablesaw, most cuts will direct dust down through the table insert. All it takes is just a little downdraft there to keep the dust contained. The problem is that most saws are so open underneath that a vacuum cannot achieve this.
Also, if you make multiple cuts to simulate a dado (I do this a lot), or if you have a weak saw that needs multiple passes to make a cut at full depth, the open slot left by this will act as a guide to direct dust back through. I can watch a ribbon of dust shoot out of that slot as I cut (I have good lighting on my saw). Tenoning is also messy for me, and I've been thinking about how to improve this (a "guard" with paint brush edges perhaps).