It's a running joke. Manhunter has been obsessed with them since JLI.>>107792136
John had the power of a Guardian during Mosaic and used it all up to revive Katma Tui. Hal's made a sentient construct before in the Silver Age when he was still trying to wiggle out of Carol proposing to Green Lantern. Kyle had God-tier powers when he first started calling himself Ion, but gave it up to revive the Guardians of the Universe.