Marcus Berkmann: The decline that no band can avoid

The thing is that rock groups do occasionally break up. It doesn't happen as often as it used to: musicians know only too well the value of the brand, and the rather more modest value of themselves as solo artists. But even the best bands may eventually realise that they have done everything there was to be done and said everything that was to be said.

REM's split is a shock, but it's not wholly surprising. Michael Stipe, Peter Buck and the goofy one strived for years to stay fresh and different and worthy of our attention. And yet, in some ways, they followed the most conventional of career trajectories. Other than die in a plane crash – which would have been asking too much – they have barely put a foot wrong.

We begin, then, with the early, difficult albums that all the rock boys love. Stipe's vocals were unintelligible, the guitars were turned up to 11, and your mother wouldn't like it. Nonetheless, these albums made their reputation. Rock boys are still arguing in pubs over whether Document was better than Green, barely noticing that their girlfriends have run off with someone else, or each other.

Their credibility thus assured, REM could move on to a brief but potent spell of global megastardom. Out Of Time and Automatic For The People are the ones everyone bought: you, me, Gordon Brown, Barbara Cartland – everyone. In "Shiny Happy People" the band created a single so infuriatingly catchy they couldn't bear to hear it again, let alone play it.

But behind the jolly tunes lay an overflowing of invention that just happened to chime with mainstream tastes of the time. Far from "selling out", as the rock boys would have it, REM probably didn't know themselves how they had done it.

Thereafter they had to endure the third classic stage of a band's life: slow and inexorable decline. Each new album got five stars, but no one was fooled. Whatever they tried – something different or something much the same – it never quite worked. I have many of these albums. You may have too. Gordon Brown probably took all his to Oxfam.

And now they are gone. Splitting up really was their only remaining option. Re-forming is obviously next on the list.