Is this the main reasons and logics why the cadet branches in the royal family exist?

In history, why did there exist the so-called cadet branch in English? First of all, as long as a monarch has more than one son, this situation will happen. Because the throne is exclusive, unlike property that can be divided equally, if the monarch has four sons, only one of them and his male descendants can inherit the throne (reasonably, the eldest son in principle), so The second, third, and fourth sons of the monarch and their male descendants are bound to be unable to inherit the throne, and they will therefore form the cadet branches (aristocratic family with royal blood). This is the reason and logic for the existence of the royal branch.

Anonymous2021-04-06T18:22:42Z

The cadet branch is just the younger sons and their families, and nothing more. The family generations simply exist.

Anonymous2021-04-06T17:47:28Z

They happen as a matter of course, but generally the senior line continues and is the only one that is relevant. Everything passes to the eldest at each point in the succession. If for some reason there is a shift to a cadet branch, that becomes the senior line but the dynasty generally remains the same. Thus Victoria inherited as a Hanover, as the daughter of the fourth son of George III.

Anonymous2021-04-06T17:27:14Z

There's no special purpose to them.  "Cadet branches" is simply what they were called.  It's just a name. It doesn't really mean anything more than "younger brother's line of descent".