I feel that the devil is in the edge cases and this allows you to have the freedom to say "ok I want to try for 1.0 match between everything, I can accept 0.98 match, and files which have less of a match it can detail notes for and I can manually approve them". So for things where the languages differ too much for specific patterns such as maybe an event handing module, you can allow more leniency and tell it to use the target languages patterns more easily, without having to be so precise as to define every single transformation as you would with a transpiler.
