Shock group D defeats to Japan and Honduras, both by a 1-0 scoreline, sent the Spanish packing, with El Mundo, perhaps slightly prematurely, declaring "a return to the dark ages" on Monday.
Sports daily Marca more circumspectly lamented "a sad end for a team that arrived at the Games full of hope and aspirations".
The Spanish players were furious with Venezuelan referee Juan Soto after he turned down two penalty claims in the second half on Sunday in Newcastle.
After Spain's senior side majestically swept aside all before them at the World Cup and European championships, their under-23 side presented an ugly image to the world by angrily surrounding the referee at the final whistle.
"Spain said goodbye to the Games with a dismal cocktail," Marca wrote, complaining of "bad luck, bad refereeing and a terrible image at the final whistle as a result of the build-up of tension during the match."
Spain's exit deprived them of a chance to add an Olympic title to their world and European crowns, which had helped lift a country struggling with rising unemployment, sweeping austerity measures and a banking crisis.
El Pais daily said the Olympic team's performance in London, and the players' behaviour towards the match officials, had damaged the image of Spanish football.
"Football has never gone well with the Olympics, but with the football brand that currently sets the country apart it was the right time to return the sport to the summit it scaled in 1992," the paper wrote, a reference to the gold medal triumph at the Barcelona Games.
"But it not only fell off a cliff, it did so verging on the ridiculous against opponents of little pedigree like Japan and Honduras. A total failure."
Writing in As sports daily, columnist Alfredo Relano compared Spain's flop to times past.
"It was a step backwards, a trip down the time tunnel that reminds us that everything wasn't always so great," he wrote.
"That we have experienced exceptional times and we have to be prepared for when they come to an end."
El Mundo described the shock of seeing Spain humiliated on the football field after a period of unprecedented success as "a fearsome blow to the stomach, one which leaves you winded".
Former Spain striker Fernando Morientes acknowledged that the Olympic side had not been "up to the task" but said he had faith the young squad, most of whom helped Spain win the European Under-21 title last year, would come good.
"This team is an exceptional group in every sense and it would be wrong to apportion blame," Morientes wrote in El Mundo.
"They are sure to bring us a lot of joy. We have faith in them, they are the future."