I have watched Brexit avidly but comfortably from across the pond for the last two years. Every PMQs Corbyn has got up and, in the earlier days, ignored Brexit entirely, and now, he complains about lack of clarity and progress by the Government. While he and his party have never had any clear position on it, by design. The Tories' current position of hard Brexit or bust may be insane, but at least it is a position. The Lib Dems and SNP have one too. But not Labour.
So while this "talking point" may have been noticed by the Mail and Telegraph, it has been apparent to many of us for some time.
If Labour had kicked Corbyn out for, say, Starmer, and taken a clear soft Brexit or even Remain position, they could have long ago taken Government from the Tories, who have obviously badly screwed up everything in Brexit that it is possible to screw up.
On the other hand I am keeping my fingers crossed for the incredibly unlikely event of a unity government under Ken Clarke.
TL;DR: philpem is completely correct.