"Now Lincoln and Argo are neck and neck," wrote Indiewire's resident Oscarologist Anne Thompson on Monday after Argo lifted the best acting ensemble award at the Screen Actors Guild awards and the best film gong from the Producer's Guild, two of the most reliable bell-weathers for the best picture Oscar.

The weekend's activity at the guilds also confirmed the locks Anne Hathaway and Daniel Day-Lewis have on their Oscars and strengthened legitimacy of both Tommy Lee Jones and Jennifer Lawrence in their respective categories. If the DGA give their directors gong to Ang Lee on Saturday, we could be in store for one of the most scattered Oscars ceremonies in recent memory, with Argo taking home the big prize, Ang Lee and Spielberg divvying up the rest of the major awards between them, an acting trophy apiece for Silver Linings Playbook and Les Misérables, and maybe a little something for Michael Haneke.

Forget a good old-fashioned sweep. Welcome instead to the Mr Potato Head Oscars – a frown from that movie, an arm and a leg from this one, a smile from that one over there.

The more statistically inclined Oscar commentators have rushed to patch up their precedents. "One of the most reliable 'rules' throughout awards history has been that a film cannot win the best picture Oscar if it hasn't even been nominated for the best director Oscar," wrote Hollywood Reporter's Scott Feinberg. "The logic of this rule has long gone unquestioned because, well, there hasn't been a reason to question it: only three films ever – and only one in the last 80 years, Driving Miss Daisy (1989) – have defied it."

Over at Awards Daily Sasha Stone pointed out that "Argo has to overcome history in 3 different ways to win this year."

Maybe, but best film / best director splits, which use to happen roughly once a decade, have happened four times since 1998. And while best actor and actress used to follow best picture the majority of the time, in the last decade only three best picture winners – Million Dollar Baby, The Artist, and The King's Speech – have generated heat for their lead actors. Increasingly, actors win awards for their work in small, low-budget indies in which they gnaw off their left leg.

The last film to pull off a sweep of all top five categories – best picture, best director, best screenplay, best actor, best actress – was Silence of the Lambs, over 20 years ago. Increasingly, sweeps are the rarity, not splits.

The academy has always liked to "spread the wealth", but this is something different. It testifies to a much larger fragmentation that has to do with the way business is done in Hollywood. In a nutshell, the global blockbuster economy has scooped out what remained of the American movie business, sending it to the hills, from which it makes the occasional darting foray, under cover of one of the studio's specialty divisions, or some pocket money from HBO.

As Spielberg himself noted in 1997:

It is getting to the point where only two kinds of movies are being made, the tent-pole summer or the Christmas hits or the sequels, and the audacious Gramercy, Fine Line or Miramax films. It's kinda like India where there's an upper class and a poverty class and no middle class. Right now we are squeezing the middle class out of Hollywood and only allowing the $70m-plus films or the $10m-minus films.

The middle-class he's talking about is the same vegetable patch in which the Academy used to grow it's prize pumpkins: middle-brow, mid-budget, prestige pics like Driving Miss Daisy, Amadeus, Dances With Wolves, Gandhi and Out of Africa, which hymned the moral efficacy of a single individual against a backdrop of historical turmoil. It wasn't quite a genre, but a style of film-making – a plush, roseate humanism, with sunsets to match – whose precedents stretched as far back as Lawrence of Arabia and Gone with the Wind.

Well, that film is dead, and the Hollywood that made it long since vanished. As one Disney producer recently remarked, "Everything in the middle is toast."

Look at the Oscar races of recent years and you'll see the same pattern of blockbuster versus indie, big-budget versus small: Gladiator vs Traffic, Chicago vs The Pianist, Avatar vs The Hurt Locker, Hugo vs The Artist. The David and Goliath storyline has not become an Oscar season cliche by accident. In this near annual face-off, both nominees have something the other one wants or lacks. Goliath has the technical polish, the effects, the box office, the gravitas. David frequently has the acting chops, the human scale, the warmth. Combine them and you'd have quite a picture. Combine them, in fact, and you'd have precisely the kind of Oscar winner your mama used to make, combining epic sweep and intimate detail, and sweeping all the main categories.

This year, Lincoln is as close to that endangered species as any. It has received more nominations than any other film (12) and packed a hefty punch at the box office ($164m+). It has historical sweep, awards-worthy performances and mahogany-hued gravitas. And yet the very thing that won the critics over – Spielberg's renunciation of all things Spielbergian – gives it a wobbly front wheel as frontrunner.

On the other hand, we have Argo, a solidly directed political caper which in another era might have earned its director four stars and a "good job" from the general public, but whose jaunty mix of geopolitics and show-business savvy – together with an underdog status only cemented by Affleck's director snub – now put it neck-and-neck with Spielberg's keening thoroughbred.

After a race of this intensity, the ceremony itself, on 24 February, is guaranteed to be a let-down. It always is, but this year we have such a terrific set a nominees – the best in years, by all accounts – that it seems a genuine shame to whittle them down. They look so strong together, yet no one truly owns that crown.

So enjoy it while it lasts. All eyes now turn to the DGA on Saturday: will we see the coronation of Affleck? A mighty Spielberg elbow, getting Lincoln out ahead again? Or will Ang Lee snatch it from under the noses of both men, as he has a habit, and history, of doing?