Putting too many ideas together at once can ruin them. Ideas need room to breathe. In this case, two perfectly normal ideas are forced to share a single handle under the guise of saving space, time and material. But it is clearly a toxic combination, and absurd. The presence of a toothbrush on one end may not significantly affect the toilet cleaning function; but the presence of the toilet brush destroys the usefulness of the toothbrush. This kind of interaction is important to consider when designing things.

If we take a smoky room, and start adding nonsmokers to it, it has no effect on the air quality until nonsmokers begin to displace smokers. But start adding smokers to a room with clean air, and each smoker measurably contributes to destroying the air quality. Depending on the size of the space, it may require only one smoker's preference to trump the preferences of many.

This is a directional effect. In one direction the effect is nothing; in the other it is everything. Smokers, noise makers and other polluters frequently seem to miss this point when they argue for laissez-faire equality. They try to equate things that are not equal. Adding a spoonful of vanilla pudding to a bucket of sewage does not turn it into vanilla pudding. But adding a spoonful of sewage to a bowl of pudding does turn it into a bowl of sewage.

A common gripe is that people don't know how to program their VCRs, and they get confused juggling all the remote controls that operate the TV, cable box, VCR, stereo, etc. The remote control was meant to be a convenience, as was the VCR. But because each new piece of gear comes with a different confusing interface, we are continually forced to learn new and horrible ways to do things that should be simple. Too much convenience becomes inconvenient.