It sure seems that way. It would make [i]some[/i] sense if weapons, armor, and class items ONLY dropped as engrams, and the Cryptarch always decrypted "leveled" "class-appropriate" loot. Then a single Engram drop would be a decent prize for any specific Guardian. But that's not what happens. Instead you have (apparently) total randomness, where you might get a legendary primary weapon (not an Engram) or an Engram of a primary weapon that when decrypted is a POS. Whether you killed the head boss baddie, or got last place in the Crucible.