Okay, so perhaps not quite 'everything', but come on. Since the last general election 13 comedians have appeared on Question Time, and Russell Brand will make it 14 next week. The ubiquitous Nigel Farage, leader of a protest party with zero MPs and a manifesto comprised entirely of bits of old Jeremy Clarkson jokes, has been on 8 times. The "dragons" of Dragons' Den have appeared 4 times between them. Scientists have appeared just twice. Katie Hopkins from The Apprentice has been on as many times as all scientists or science writers put together.

I may have missed one somewhere, but as far as I can tell the last guest from the world of science to appear on Question Time was Professor Colin Blakemore, way back in November 2011. One blogger, Callum Hackett, went through a year's worth of episodes up to last May, counting appearances by profession. Only one scientist had appeared in all that time.

In the year since he wrote that post, no more have surfaced. Brian Cox the actor is far more likely to appear than Brian Cox the professor. Literary performance artist James Delingpole is more likely to appear than any meteorologist. Peter Hitchens is far more likely to appear than any expert on drugs or addiction - as his his nemesis, Russell Brand. A man who infamously claimed that "not everybody needs to be asked prior to each insertion" is more likely to appear than any expert on criminology or sexual health. When the e-mails of climate scientists were hacked, this is the show that brought on Marcus Brigstocke to defend them against the conspiracy theories of Melanie Phillips.

Question Time is, in short, a pretty miserable failure when it comes to informed debate. The bulk of panellists are drawn from the same upper-middle-class, upper-middle-aged pot of journalists, lawyers and politicians, and are often profoundly ignorant on topics outside of that narrow culture. Science, sex, the internet … attempts to tackle anything outside their world result in bewildering exchanges that confuse more often than they inform. It was Question Time that taught me I should be careful when doing my work on the Facebook.

A great example of this occurred in last night's show, which addressed the mysterious topic of Scottish independence by pitching a single advocate against an array of opponents that included George Galloway, and noted Scottish politician Nigel Farage. Parties that actually have elected representatives in Scotland were bizarrely excluded. David Dimbleby mounted a tetchy defence of the policy, but his argument that it didn't matter because the audience were "split fifty-fifty" on the issue only dug him deeper into a hole. The obvious retort: if it's so important for Question Time's audience to be balanced, why not also the panel?

But then the 'balanced' audience, like so much else about the program, seems little more than a television gimmick; one of many conceits in a political theatre that tries to replicate the features of a serious debate without ever really understanding their meaning or importance. Yes, it's possible that an imbalanced audience could introduce a subtle bias into proceedings, just as it's possible that putting tomato in a kebab adds a few calories to it.

Increasingly though – perhaps accelerated by the explosion of the #bbcqt hashtag on Twitter – even the pretence of heavyweight political discussion seems to have given way to the courting of petty drama and minor celebrity. Appearances by the likes of Russell Brand are trailed well in advance. David Starkey's particularly nasty behaviour, much of it directed at women, should have seen him denied a platform until he could learn how to act like an adult and treat his colleagues with respect. Instead, the BBC have rewarded his tantrums with a place or two in every series for his.

Not that there's anything wrong with knowledgeable comedians like Marcus Brigstocke or Russell Brand being on Question Time, or producers trying to bring some entertainment into the show - I like a good argument as much as the next person. The problems start when the noble aim of getting people to watch an informative political debate degenerates into a single-minded quest for eyeballs at any cost. By all means keep the comedians and the bust-ups, but would the show really be so dull if they booked a few guests with genuine expertise in the topics being discussed?

@mjrobbins