>Decompilation to C (and even C++!) has been done automatically for 2-3 decades at least.

Only in a very rudimentary sense and definitely not in a working compilation (much less binary equivalent) sense. LLMs have turned this from a gimmick for static analysis into something that actually works pretty well for recompilation projects.

> Only in a very rudimentary sense and definitely not in a working compilation (much less binary equivalent) sense.

Binary equivalence is the easy part; the hard part is getting something that classifies as readable C. LLMs do not really help reach the "working compilation" part but benefit from it.