The supposed origin for adakites (slab melting) is almost certainly
wrong, according to what I hear.
But who am I to interfere? I am not a geochemist.
I'm not sure we know what Earth's first felsic crust was. It may have
been TTG, but it's beginning to look like we don't actually have an
outcropping sample of the genuine first stuff anywhere (even if
people insist to the contrary).
I still side with the minority.