It has come to my attention that Marlon Brando was not Italian. Yes, the name “Brando” comes from the German name “Brandau”. The actor who so memorably played Don Corleone did not have a drop of Mediterranean blood in him.

Another scandal! Elizabeth Taylor, despite portraying Cleopatra, was not actually Egyptian. I’m as shocked to hear about this as you are.

Yet more controversy! Peter Sellers, who performed the role of Chance in Being There, did not have developmental disabilities. He might have been a high-functioning sociopath. But that is not the same thing.

Now, this is obviously outrageous. At a minimum, I’m calling for the Godfather to be removed from circulation and all Brando’s scenes replaced with scenes where John Travolta plays the role of Don Corleone.

Okay, enough of that. One must be fair to the racial, cultural and gender essentialists of the left and admit that it would be preposterous to claim that one’s background has no influence on one’s artistic potential. Would The Sopranos have been as good if the cast had for some reason been Irish-American? Of course not. Half of the actors were essentially playing themselves. But would Liam Neeson be a more convincing Italian-American mobster than Steve Carell? Well, sorry Steve – but yes.

I have never cared too much about attempts to have white actors be prevented from playing ethnic minority characters, or straight actors be prevented from playing gays or lesbians, or “cis” actors be prevented from playing trans people. The films and TV programmes in question always seemed so dire that it was hard to believing that minorities even wanted to be involved.

For example, were black actors really crying out to be involved with the shambling corpse of The Simpsons? I am of course sympathetic to Harry Shearer, who so timelessly voiced the cheerful African-American doctor Julius Hibbert, when he says that it is ludicrous for the creators to impose a rule that white people cannot perform as black, Asian or Hispanic characters when the job of an actor is to pretend to be somebody they are not. If you asked random Americans what kind of person they thought performed as Julius Hibbert I guarantee that most people would think it was an African-American man. After all, one cannot see him. But The Simpsons has been so bad for so long that one might as well be outraged by people redecorating a ship as it sinks. As for the white actor who gave up her job voicing a black girl on the cartoon show Big Mouth, well – involvement with that gross, sinister “comedy” about children and sexual hang-ups is surely a hindrance not a blessing for an actor. Having it on your CV is like having a reference to your extensive criminal record.

Still, one feels as if we are entering bizarre territory when Zoe Saldana feels obliged to apologise for playing Nina Simone. Now, a white person playing Simone would be ridiculous. One could share people’s grievances then. But Ms Saldana is black. She just is not black enough. The irony is that Nina apparently had a terrible script but putting silly words into the singer’s mouth was deemed less significant than having an actress with a slightly wrong skin tone.

Commenting on the ethnic make-up of a cast is easier than commenting on the script

I wonder if this subpar media and this subpar criticism are separate or related. One does not have to be the kind of aesthete who thinks art and politics somehow inhabit wholly different realms to think that there is an excess of stuffy-minded political moralizing in modern criticism. I have heard roughly two million five hundred and eighty six thousand times more about American Dirt than any other recent novel, for example, far less because of its artistic merits of deficiencies than because of its alleged appropriation of the culture of Mexican migrants.

This has something to do with our political climate, of course, but it also has something to do with our media economics. Everybody wants to be a critic nowadays. The bar to entry has never been lower, what with blogs, Twitter, YouTube et cetera. But there is a problem: not everyone has something to say. Happily, commenting on the ethnic make-up of a cast is easier than commenting on the script, the cinematography, the themes, the performances et cetera. Anyone could do it.

It is also more controversial and guarantees that more attention will be drawn. If a biopic just has a lazy script and flat performances then nobody is going to read your coverage of it except people who had an interest in the film in the first place. If you can make it political, on the other hand, you can attract the eyeballs of people who are interested in The Issues, and in the drama, as well as in the film. Years after it was made, journalists are still wringing material out of an uninspired Nina Simone biopic. It is easy and marketable. Win-win!

This is fine for people who make movies as well – or, come to that, television or literature. None of them want to take big artistic risks because they might alienate their audience. It is much safer to create an efficient exercise in box-ticking. Extension of a successful franchise? Uh huh. Opportunities for merchandising? Yes. Buff yet soft-featured star? Of course. If a few of those boxes keep humourless critics happy then, well, all the better. What’s the point of trying to create something valuable if you can just take a shortcut through the minefields of the fanboys and the scolds.

Again, I don’t want to push my arguments to farcical lengths. Of course, identity is not so irrelevant to dramatic performance that Nick Cage could be considered for the role of Martin Luther King, or Lena Dunham for Aretha Franklin. But the elevation of this general, commonsensical idea to the status of an ironclad moral law is another depressing case in the unilateral scoldifying of the mainstream, and the desiccation of modern art and media.