Now, this has my full-hearted support:
In the shower yesterday, I was struggling with some idiotic substance called "shower scrub". (It was in a bottle that you couldn't hold, squeeze and collect from, while at the same time trying to wash yourself with the other hand. You lost most of it down the plughole.) And I remembered the late Alan Coren's column about things invented in the wrong order.
So here, Alan, is another for your list: that brilliant new invention for the shower: a washing agent in solid form; self-cleaning; economical; easily handled; no caps to lift or seal; no packaging but a discardable paper wrap; unable to be spilt down the plughole; and giving an all-day perfume to your bathroom! It's called "soap".
Apart from being handier than the alternatives, soap also has more admirable metaphysical properties: its solidity is reassuringly definite, giving users a thorough sense of the objectivity of the world; and it looks like what it is, rather than like any number of possible substances.