Why are compressed mass spectra associated with soft decay products?

Question

Compressed spectra, as produced by BSM models like the mUED (minimal Universal Extra Dimensional) model and the MSSM (Minimal Super Symmetric Model), are associated with soft decay products. The literature tends to state this as a known fact, and although it does seem intuitive, how would one explain the reasoning for these low-energy final state objects, explicitly?

Thanks!