You’ve probably heard by now, Jack Dorsey, the co-founder & CEO of Twitter, resigned effective yesterday. The news had been rumored yesterday morning, with CNBC reporting that Dorsey’s departure was imminent. By afternoon, Dorsey had confirmed it, tweeting an email he sent to employees announcing that he was stepping down.

Dorsey’s email mentioned his successor, Parag Agrawal, and thanked employees for their ambition and potential. He even mentioned Bret Taylor, who is the President and COO at Salesforce, and is now Chairman of Twitter’s Board.

More interestingly, however, is what Dorsey had to say about Mark Zuckerberg. To be fair, he doesn’t actually mention him by name, but read this passage and tell me it’s not a direct shot at Facebook’s founder and CEO:

If that wasn’t direct enough, Dorsey had even more pointed words. “There aren’t many companies that get to this level,” Dorsey wrote. “And there aren’t many founders that choose their company over their own ego. I know we’ll prove this was the right move.” 

Even without mentioning Zuckerberg by name, it doesn’t take much to see the connection. No other founder exerts as much control over a company as Zuckerberg–who literally owns a majority of the voting shares in Facebook–does over the company he founded in his dorm room at Harvard.

More than that, no other founder is as closely associated with the dire problems facing a company as Zuckerberg. In confirmation of what most people already knew, Facebook Whistleblower Frances Haugen made it clear that Zuckerberg is fully aware of the harm caused by the company’s pursuit of “engagement at all cost,” but isn’t willing to make changes.

You could argue, then, that Facebook’s biggest problem is Mark Zuckerberg. If there was ever a “single point of failure” in a company, this is it.

If you think I’m reading too much into the email, consider this: Dorsey has mostly been an absentee CEO at Twitter for years, spending more of his time leading Square, the payment processing company he founded, where he is also CEO.

That’s not to say that Twitter won’t benefit from having a full-time CEO, as activist investors have pushed for in the past. Dorsey was known to pay little attention to areas of the company that didn’t interest him and was notoriously slow to make decisions.

At the same time, however, Dorsey was known to delegate most decisions to his deputies anyway (most notably, Agrawal). My point is that I’m not sure Dorsey had himself at the top of the list of “founder CEOs that have to go.”

It’s fair to debate Dorsey’s reasons for leaving, and more curiously–his reasons for leaving now. On one hand, the fact that Dorsey resigned, effective immediately, came as a surprise. No one was even in the office as the company gave everyone a “day of rest.” 

On the other hand, Dorsey’s departure almost seems overdue. Twitter has been unable to keep pace with its tech brethren over the past few years in most of the metrics that matter. Even as it has accelerated the pace of launching new products, and has recently reported solid revenue numbers, active user growth has mostly stalled. 

Regardless of his reason, I think it’s clear that he took the opportunity to make a statement about founder CEOs in general, and one notorious tech CEO in particular.