Why do assembly programs have separate segments?

Question

Why do assembly programs load segments (.data/.bss and .text) into separate memory blocks instead of loading both the data and the code se

Answer 1

No, I think you understood wrong, segmentation concept in not only used in assembly, every machine specific high level languages (like C, C++, Basic, Pascal, etc.) use segments internally.

Because every C and C++ programs are compiled to assembly language by GNU compiler (in the case of Ubuntu), the compiler will put appropriate datas to appropriate segments and the GAS assembler will convert this assembly to object code bytes.