Optimists have scoured the dictionary for superlatives to describe the future of internet education. But the cult of the Mooc – massive online open courses – took a blow last week when one of its leading Silicon Valley pioneers, Sebastian Thrun, described it as a “lousy product”.

Students taking Mr Thrun’s online courses at Udacity performed far worse – and dropped out in far higher numbers – than those with a human instructor. Mr Thrun, who invented the self-driving car, is at least temporarily dropping out of the business. Luddites everywhere will be feeling vindicated.

Yet the need to reinvent US education is more pressing than ever. If America’s college dropout rates are not persuasive enough – nearly half of US students fail to complete their four-year degree within six years – the fate of those who make it ought to be. Graduate earnings have fallen 5 per cent since 2000. The college premium is still there but only because the earnings of those with a high-school diploma have dropped by far more. Meanwhile, the costs of getting a degree continue to rise, which means the trade-off of taking on ever larger debt to boost future earnings keeps getting weaker.