Fans cant blame the club on this one, because there was a collective delusion on the Caf and with Man Utd fans online that DDG was by far the best keeper in the world. Nobody else ever thought of him that way but it was ingrained so deep that, for years, I avoided all DDG related threads on the Caf because I knew it'd be a circlejerk around a below average keeper. He was, and probably still is, the best shot blocker in the world, there's no denying that. But that's just one aspect of the goalkeeper role and he's below average to abysmal in all the others.
And he used to make almost €2M/m, 15 times the average wage of a GK in Ligue 1 (I know we're a poor league, but still). Unless he/his agents make it known that he's willing to play for very cheap, he's going to have a hard time finding a spot in Europe.