I mean, it does, but that’s not what TFA’s problem statement is, and I can imagine why one may not want to immediately take apart the expression into assembly-l

I mean, it does, but that’s not what TFA’s problem statement is, and I can imagine why one may not want to immediately take apart the expression into assembly-like SSA let $0 = f a b in let $1 = g $0 c in ... and instead leave some original structure in place and some tree-level simplifications available.