FIFTY ARTISTS. Three microphones. Two minutes each.With a program as unwieldy as a 2023 reprise of Jean Dupuy’s 1974 epic “Soup & Tart,” it’s really about what you remember, what sticks out. Earlier this month at MOCA Geffen, the poet Elaine Kahn showed up with her baby in arms. When it was her turn, she asked the audience for a diaper. A little commotion, people murmured and squirmed on their cushions, then a diaper was passed up front. Kahn squatted down and changed her kid, right there on the floor all in two minutes. That made an impression.Dupuy’s event, held at the Kitchen’s loft in TriBeCa