Why are there so many Windows boot brokers after bootmgfw.efi?

Question

Windows

I became interested in the issue of loading the OS, namely Windows.
I read about the fact that there are MBR and GPT, their differences and other information
One of the sources www.mistyprojects.co.uk/documents/BCDEdit/files/gl... says that bootmgfw.efi (UEFI) and bootmgr.efi (BIOS) are both boot managers and bootloaders of the OS itself.

Boot Manager - a utility that allows multiple operating systems to be loaded. On Windows NT 6.* systems the Windows Boot Manager is bootmgr (BIOS) or bootmgfw.efi (UEFI). bootmgr and bootmgfw.efi function as both boot manager and boot loader (OS loader) .

And in the definition of Boot Loader, it says that this is directly the bootloader of the OS itself and for Windows it is winload.efi (UEFI) or winload.exe (BIOS)

Boot Loader - operating system specific boot loader, loaded by the Boot Manager - Windows NT 6.* boot loaders include winload.exe / winload.efi / winresume.exe / winresume.efi. The Windows NT 6.* boot managers (bootmgr and bootmgfw.efi) are, in addition to being boot managers, also boot loaders.

Also at the very end, in the information about what winload.exe and winload.efi are, it says that these are bootloaders launched by the bootmgr.efi and bootmgfw.efi files. And in https://social.technet.microsoft.com/Forums/exchan... in the penultimate comment (which has 3 votes. Unfortunately there is no link to the comment itself) it says that bootmgfw.efi loads a BCD file, and BCD is already loading the winload.efi file.

Actually questions:
1. Where it was said that bootmgfw.efi and bootmgr.efi are both boot managers and boot loaders of the OS itself, is everything said right? If so, why are BCD and winload.efi needed?
2. If bootmgfw.efi is a Microsoft bootloader and it starts BCD, and that one is already winload.efi, then why such a chain? Why doesn't bootmgfw.efi directly start Windows, but delegate it to other files?

Also, the description of VBR says that it is a synonym for PBR and that the code from PBR starts bootmgr, and that one is already BCD (and BCD, as I understand it, loads winload). Yes, I understand that this scheme is only in the Legacy BIOS, But the question is:
3. Why doesn't the code from PBR start Windows directly? After all, it is Windows that forms PBR during installation and, accordingly, you can put the OS loader there.