Does prestashop 8 FO controllers directly depend on legacy classes?

[John Zaw]

I am reading prestashop 8 documentation and found that FO controllers directly depend on legacy classes. And I found that legacy code is gradually replaced by modern core classes. So, why FO depends on something that will be removed in the future?. I got a little confused. My main questions will be
- When core classes or prestashop bundle need something from legacy classes, they use adapter. But when FO use legacy classes, why it directly access to legacy classes?

I am new to Prestashop and trying to understand design patterns and structure of prestashop. I apologize if I made any mistakes in my question. Thanks for all answers. Have a nice day.