Yeah, that's also my theory, and even if you could get it functioning in a way to benefit gaming, it would abso-fucking-lutely make the thermal situation worse.
usually AMD nowadays severs the unused parts for core unlocking. AMD occasionally had parts between 2009-2013 which could be unlocked (e.g athlon tri cores to quad cores, 6950 to 6970, r9 290 to r9 290x) but hasnt really happened since then.
You had to win the silicone lottery to do so though. Or the supply and demand lottery, I guess. Tri core CPUs started as quad core silicon where one of the cores was damaged during manufacturing, but as the manufacturing got better they started having fewer mistakes and started supplying the price bracket with perfectly working quads with one core disabled.