RJ, I think you're on track with the late historical use of decoction. It sounds to me like you are an experienced brewer and maintain good brewing tradition [repects]. My point is the historical use of decoction, (lit. 'to boil down') in brewing was primarily for poly-saccharide (starch) conversion to sugars (at one time). The Romans used 'Decoctionem' as the word meaning to boil-down to an essense in wines medicines and beer. The Romans adopted techniques from the Greeks, Greeks from Persians, Persians from Babylonians, Babylonians from Hittites, Hittites from Sumerians from which we get a rich heritage of brewing, (there are over 18 descriptive terms in Sumerian Cuneiform for 'beer' and beer making, re John A. Halloran's Sumerian dictionary). In other words, anyone doing a 'boil' reduction is actually 'decocting' following with an earlier Roman history, (actually much earlier than the Roman term we adopted in English), of the act that the Germanic tribes later copied and adopted.
Maybe i read too much...Me thinks we innovate too much also
Anyhow, I think we both have good points to make but decoction is not as limited a technique as we might think at first glance.