German Brewing

There are many posts about decoction in the forum but I do not see any post that discusses the essence of decoction mashing.
These are the hypothesis to discuss. I am asking all to contribute more hypothesis, to provide evidence and comments that confirm or contradict the hypothesis contributed. These hypothesis assume well-modified malts.
H1. The essence of decoction is in the boiling of the solid grains contributing maillard products to the finished beer
H2. The longer you boil the grains, the more maillard products are generated by the decoction
H3. The liquid portion of the decocted grains must be combined with alpha and beta amylase after the decoction to breakdown additional starch freed by the boil
H4. Decoction natually lowers the pH of the mash (eg from 5.4 to 5.2) so that when hops are added during the boil the bitterness in the beer is softer than what it would be otherwise

Looking forward to a helpful discussion -

I believe maillard reactions to be a side effect, and not a significant factor when decocting. In a properly handle modern decoction, they barely occur, no more so than say, in the boil kettle for the main wort. Unless the decoction is handled in a specific way, with a high pH and greater boil intensity and duration, the effects are negligible.

The real purpose, imo, is to break up stubborn starch particles in hard pieces of grist, as well as the husks, to yield better extraction efficiency. There's also some additional flavor extraction from the husk material. Better efficiency, and more malt flavor while keeping the beer as bright as possible, as well as carrying over less of the hot break to the boil kettle - hot break will form during the decoction boil, and a significant amount will be filtered out by the grain bed during the lauter.

Decoctions will give a slightly higher yield since it frees up more starches. One can easily see this when performing an iodine test before and after the boil.

Decoction schedules are adjusted to the degree of modification of the malt and towards the desired beer style.

There is a pH drop, but it won't be as drastic as from 5.5 to 5.2. I observed a drop of 0.1 usually.

Decoctions speed up the sparge process since a clear run is obtained earlier. It already boiled off some proteins and a large portion of that protein break remains in the sparge tun.

Despite what the amateur press says, tannin extraction during decoctions are a real concern. Usually this is handled by discsrding 30% of the husk or an all out Spelzenmaischverfahren.

For wheat beers the decoction boils assist in further breaking down the stubborn wheat - another alternative is to double mill at increasingly smaller grind settings.

Of course, the decoction must be returned into a mash with enough enzymes to convert the extra starches. Starches are not freed endlessly. On a triple decoction schedule the third decoction achieves very little in this respect and is thus either thin or normal, but rarely ever thick (1:2 ratio)