A good hot break will go a long way to the creation of clear wort. It’s not just proteins that are creating the hot break reaction- in addition to the proteins, other polypeptides present in the wort will combine with tannins or polyphenols and become part of the hot break, due to their electrical charges. Other reactions are happening during the boil also- DMS precursors are driven off, isomerization of hops oils, color development due to maillard reactions, concentration of the wort, and the pH of the wort will drop, primarly due to the precipitation of calcium phosphate. Calcium in the brewing water reacts with phosphates from the malt, and this reaction will lower the wort pH.
The next item to discuss for wort clarity is then the ‘cold break’. Cold break happens when the finished wort cools. Cold break is again mostly proteins, but another group of proteins that need to precipitate out of the wort to form a clear wort. The lack of a cold break is generally not a big issue in the flavor of the finished beer- instead it is mostly an aesthetic issue but it can affect long term stability of the beer. For most homebrewers, that isn’t an issue either, as we rarely have to worry about that, unlike commercial breweries. Still, from an aesthetics standpoint many brewers would prefer to have clear beer to serve to friends and guests.
Quick chilling helps form a good cold break, and kettle finings such as whirlfloc or Irish moss can be helpful in that reaction.
Here is a hydrometer sample of wort straight from the kettle, with both the hot break and cold break suspended in the cooled wort: