Not to beat a hopefully deceased equine but here’s an example of the kind of screw up that can happen. Starting with a model of a coffee table…
I made the Button tag active and then added geometry to create rounded ends on the top. The added geometry now has the Button tag…
…but not all of the geometry does. Now, when the Button tag is turned off, you can see what happens to the top.
Again leaving the geometry all untagged and only putting tags on the objects prevents undesirable results.