1. Syntax and backward compatibility, that is, once it appears in the standard, this thing will remain in C++, moreover, it comes from C with classes
2. "." is there, but "::" is used for statistical fields of classes (which, for example, do not even exist in Python), libraries, that is, for things that change globally.

So this makes everything more readable, and also makes a distinction between the assembly member and the object member, which was described in the link in the comment.