A wave of layoffs is sweeping startupland. But why? "Today is my last day at Revision3," writes Damon Berger, one of the victims, in a mass email. "Due to budgetary cutbacks that are a direct result of the economic meltdown, I will no longer be employed at the company." Revision3, an online-video startup, has slashed five Web-video shows from its lineup, and with it some unknown number of employees. But are we to believe that collateralized debt obligations killed "Internet Superstar"? Of course not.Yes, online advertising is headed for a slowdown — but signs of problems were present in the market well before Wall Street went into crisis. An explosion of usage had created a supply of space for ads that far outpaced marketers' demand. A recession will further temper demand. Berger, and countless like him at ad-supported enterprises, would have ended up on the street regardless. (Which is a pity, since I've met Berger, and he strikes me as personable, clever, and eminently employable elsewhere.) Revision3, best known as the home of Digg founder Kevin Rose's beer-chugging Diggnation podcast, has always been the kind of lovably goofy startup one hopes does well despite itself. Anyone who suffered through "Internet Superstar" knew the show was going down. It failed on the merits, not because of distant economic forces beyond anyone's control. To paraphrase Tolstoy: Successful startups are all alike. But every unsuccessful startup is unsuccessful in its own way. And so with all the startups whose managers have jumped on the firebus. If they had run their businesses efficiently, they wouldn't have needed to fire anyone. They are laying people off now not because of an economic imperative, but because they have a convenient excuse to cover their mistakes. Revision3 should always have concentrated on its main shows, and found cheap ways to experiment with new shows, as it's doing now. Helium.com should have figured out that there's not much money in user-generated content before laying off a third of its 110 employees. And Seesmic? Well, Seesmic should never have launched at all, good economy or bad. I'm declaring the layoff window shut. Big companies lay people off because of economic conditions; startups lay people off because their managers have fundamentally misjudged some aspect of their business. Any startup CEO who lays people off, from here on out, should be held accountable for his own mistakes. Blaming the economy for your cuts? So mid-October 2008.