"Remember that extracting wealth from the markets and transferring it from one account to another is not the same thing as 'profit', because it reduces the wealth available to actual productive investment - the corporate processes which do not and cannot change any faster than the time it takes to gear-up a factory or harvest a crop."
Nonsense. Say the price of oil changes; then all of a sudden all sorts of companies make or lose enormous amounts of money. Same thing with interest rates, the weather, natural disasters, international politics, etc. Here's an exercise for you: go buy stock in a pharmaceutical company that's waiting to get approval of a new drug. On principal, refuse to trade it even after the announcement comes out and the price spikes or plunges. Afterwards, you can give us all a nice lecture on how little you care for market liquidity.
For that matter, how do you determine a fair price to pay for your investments? Do you bring up a spreadsheet, model the company's discounted future earnings, and derive the price you're willing to buy and sell at? Of course not. You rely on the market to let you know what a fair price is. Without a liquid market, you might as well be buying stock from some guy who calls you up on the phone.
Of course, I'm going to guess that you or someone else is going to say, "But I just take the high road -- I invest in indexed mutual funds and don't try to beat the market." But what do you think the fund's traders are doing? Just sitting around all day and not trading? All you're doing is paying someone else to execute those same trades for you.