would be better to say what can you accept, what do you understand and what is still unclear. Or give us some examples, ask. Maybe there is no "much simple way"

Internally, it is a pointer. But that is considered an implementation detail, not part of the definition of a reference. There are also lots of syntactic differences and usage rule differences between a reference and a pointer, but all of that is outside of "how it works internally".

Because the C++ standard prohibits those.

There are never simple answers when second guessing the reasons for decisions made by the authors of the C++ standard. Many arbitrary seeming decisions have good reasons once you understand how deeper consequences connect through the whole language design. In this case, the relationship of reference usage rules to template inference makes more complicated references a problem. More fundamentally, a reference to a reference only makes sense based on the implementation detail of using pointers. But that cannot be assumed by the standard.

The simple clear answer is what I put in bold in this restating of what was said earlier.