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Liquid crystal elastomers (LCE)polymernetworks constructedwith liquid crystal unitsare functional materials characterizedby a pronounced coupling between elastic strain and liquid crystallineorientational ordering. When prepared by polymerization and cross-linkingin the isotropic phase, and then cooled (“isotropic genesis”),a polydomain LCE presents an extraordinary “supersoft”elastic behavior under unidirectional pulling, with a plateau-likelow elastic modulus region in the stress–strain curve, beforeturning into a monodomain LCE where a standard elastic resistanceis recovered. The physical mechanism of this behavior is of greatinterest, but still mysterious. This work investigates its origin,reproducing the experiment and succeeding to observe the plateau-likestress–strain behavior by means of large-scale molecular iso-stressMonte Carlo simulations. The results not only show that the basicmolecular mechanism behind supersoft elasticity hinges on local domainrotation and growth but also suggest that this is assisted by a newlyproposed dissipation of the elastic energy stored in the defects createdby the isotropic genesis process, explaining also the irreversibilityobserved in main-chain LCE. [ABSTRACT FROM AUTHOR]