(the precious metal Au), a means of exchange. Gold has few industrial uses, and there is no reason it should be as valuable as we have made it, but its rarity and indestructibility (and perhaps its near-useless practical value) have made it worthwhile solely as a bookkeeping device.

The rating services may be totally obsolete now for the reasons you mention and many others which have been becoming clear over the decades, but they will continue to be used to determine the value of entertainment programs simply because the business end of TV can't think of any other way to sell their eyeballs to advertisers "objectively". Without a means of assigning a precise value to that which they peddle, the suits would be out of a job. They are parasites that produce nothing of value themselves.

In today's complex arts environment, and with a saturated media-savvy public increasingly immune to commercial persuasion, the actual effectiveness of advertising is probably highly overrated. Nobody really believes any of that shit any more, but Madison Avenue has to justify its existence somehow.

Come to think of it, perhaps this inability of traditional metrics to accurately gauge the value of program content is the reason why TV is so much better now than it used to be. The advertisers have less incentive to dumb down the content for commercial purposes.