TAMPA, Fla. - “There is something about a national convention that makes it as fascinating as a revival or a hanging. It is vulgar, it is ugly, it is stupid, it is tedious, it is hard upon both the higher cerebral centers and the gluteus maximus, and yet it is somehow charming. One sits through long sessions wishing heartily that all the delegates and alternates were dead and in hell – and then suddenly there comes a show so gaudy and hilarious, so melodramatic and obscene, so unimaginably exhilarating and preposterous that one lives a gorgeous year in an hour.”

That was Henry Louis Mencken, writing in July 1924 about the Democratic National Convention that had adjourned a few days earlier at New York’s Madison Square Garden. Never was a presidential convention more grueling. It lasted 16 days and went through 103 ballots before finally anointing John W. Davis, a former solicitor general and ambassador to Great Britain, as the Democrats’ standard-bearer. Four months later Davis lost in a landslide to President Calvin Coolidge.

Ah, for the good old days, when party conventions really mattered. They may not have had a national TV audience or air conditioning; they had to make do without balloon drops, iPad apps, or a Frank Lloyd Wright-inspired stage. But nominating conventions conventions in decades past had something today’s vast high-tech pageants lack: an authentic and indispensable role in the nation’s democratic process.

Delegates used to gather every four years to select a presidential candidate. They didn’t generally need 103 roll calls to make their decision – 1924 was off the charts – but that decision wasn’t a foregone conclusion, and coming to a consensus was what conventions were for. Today, when each party’s nominee is chosen long before the delegates arrive, conventions are nothing but spectacle – hype and hoopla, a partisan pep rally on an outlandish scale. They are expensive, disruptive security nightmares, and the time has come to shelve them.

There’s nothing wrong with each side in a competition firing up its troops as they head into a showdown. And pageantry obviously has a place in American life – think of a presidential inauguration, or halftime on Super Bowl Sunday. But inaugurations still serve a meaningful function: the peaceful transfer of power in a national ceremony mandated by the Constitution. The Super Bowl is still the pinnacle of the football season; if there were no game, there would be no halftime show.

The conventions, by contrast, deprived of their essential purpose, have been reduced to an exercise in mutual self-aggrandizement. The two major parties garner obsessive press attention – media organizations sent 15,000 employees to Tampa for the Republican convention – without generating any real news. The media, in turn, make a great show of being eyewitnesses to history, when all they’re really witnessing is an immense infomercial.

Why perpetuate the charade? The parties spend tens of millions of dollars to mount these events; news organizations invest a fortune to cover them; and taxpayers kick in a thumping $136 million in additional federal funds. And for what? Most voters watch little or none of the televised convention proceedings, and these coronations have little discernible impact on how the election turns out.

The conventions have their defenders. “They create dialogue and debate and discussion about issues, and that’s a good thing,” Pennsylvania delegate John Rodgers told me last week. “Plus, it’s a celebration of our democracy.” The editors of USA Today argue that conventions “still matter” since they serve as “a wake-up call of sorts for the politically disengaged, reminding them to start paying attention” to the looming presidential election. For David Gergen of Harvard’s Kennedy School, the conventions – though too long – enable Republicans and Democrats to introduce “rising stars,” and force the parties to spell out their beliefs in a platform.

But these are after-the-fact rationalizations, hardly good reasons for clinging to a 19th-century political mechanism that the 21st century has made obsolete.

There’s only one real reason these conventions haven’t been scrapped. “It’s just tradition,” says Demetra DeMonte, a Republican National Committeewoman from Illinois and one of the RNC’s four elected officers. “Conventions are expensive,” she sighs, and the parties have better uses for the money. “But until one party stops doing it, the other one won’t either.”

It’s only a matter time. The “gaudy and hilarious” carnival that so entertained Mencken has become a relic, absurd and ostentatious. Extinction eventually caught up with Tyrannosaurus Rex. It will catch up with this dinosaur too.

(Jeff Jacoby is a columnist for The Boston Globe. His website is www.JeffJacoby.com).